MeshPit
PLA and PETG are the two to stock
Buy PLA and PETG first, and you can print nearly everything in MeshPit. PLA is the easy one. It sticks to the bed, holds fine detail and comes in more colours than anything else. PETG is the tough one. It takes more heat, resists water and bends before it breaks.
Use PLA for things that sit indoors and look good, and PETG for things that work hard or live in the heat. If you aren't sure, ask what happens to the part. If it will sit on a shelf, use PLA. If it will hold weight, flex, get wet or get hot, use PETG.
| Filament | Goes soft at | Good for | Watch out for |
|---|---|---|---|
| PLA | About 60 °C | Easiest to print. Most colours, crisp detail, little smell, no enclosure needed. | Goes soft in a hot car or direct sun. Brittle, so it snaps instead of bending. |
| PETG | About 80 °C | Tougher than PLA, bends before it breaks, and takes sun, rain and a bathroom. | Strings, and sticks hard to a smooth plate. Needs a hotter nozzle and a slower fan. |
| Silk PLA | About 60 °C | A glossy, metallic finish that looks good on decorations. | Weak between layers, so it cracks under load. Not for parts that carry weight or flex. |
| ABS | About 100 °C | Takes about 100 °C. Tough, and sands and smooths well with acetone vapour. | Needs an enclosure and ventilation, warps as it cools, and yellows in sunlight unless painted. |
| ASA | About 95 to 100 °C | Tough like ABS and made to keep its colour and strength in sunlight. | Needs the same enclosure, hot bed and ventilation as ABS, and warps in the same way. |
The temperatures are typical. Brands differ by several degrees, and a part under load softens earlier than a part sitting still. If you need the filament's number, read the spool's data sheet.
Which filament for each MeshPit project
The tools' defaults suit a 0.4 mm nozzle and a plain PLA or PETG. This is what each kind of print needs:
| Filament | Why | |
|---|---|---|
| Lithophanes | White PLA | The thin walls have to pass light, and white shows the most tones. Silk and coloured filaments tint the picture. |
| Name light boxes | White PLA for the letters and front, any plain PLA for the walls and lid | The white parts must let the LEDs through. The strip stays cool, so PLA is fine indoors. |
| Cake toppers | PLA, with the stakes wrapped or replaced (see the food section) | PLA prints crisp letters and thin stakes. Silk PLA is fine for the topper itself, but the stakes are thin and bend across their layers. |
| Project boxes | PLA indoors, PETG in a car, a shed or the sun | Snap-fit lids and screw bosses flex and heat up. PETG gives and PLA cracks. |
| Hooks, clips, brackets and holders | PETG, or ASA or ABS where a part needs more heat | These load a thin section every day. Avoid silk PLA, because the layers pull apart where the load lands. |
The Lithophane Maker and the Light Box Maker need white filament for the parts the light passes through. The lithophane guide and the name light box guide cover the rest of those prints. The Project Box Designer suits either filament, and the project box guide says when to switch to PETG. The Cake Topper Maker and Mounts, which make hooks, clips, brackets and holders, are in MeshPit Desktop.
Why silk PLA is a poor choice for working parts
Silk PLA is regular PLA blended with additives that give it a glossy, metallic sheen. The additives weaken the bond between layers. A printed part is a stack of thin lines, and its strength depends on how well each line fuses to the one below. A silk part looks solid and breaks along a layer line under a load a plain PLA part would carry.
That matters most for parts that:
- hold weight, such as hooks, brackets and holders,
- flex, such as clips and snap-fit lids,
- take a screw, because the boss splits along its layers when you tighten it.
Silk is also hard to print well. It needs a nozzle a few degrees hotter, slower speeds and less cooling to bond as well as it can, and even then it falls short of plain PLA. Strings, blobs and rough layers show more on its shiny surface.
Silk is a good choice for decoration that carries nothing, such as a trophy, a figurine, a vase, the printed top of a cake topper or the lid of a box that isn't opened often. It is a poor choice for a lithophane, because it tints the light and blocks it more than white PLA. It also suits the name-light letters badly, because the pearlescent surface scatters light unevenly. Use plain white PLA for both.
If you want the look on a part that does work, print the working part in PLA or PETG and put silk only on the piece that shows. A multi-colour 3MF from the Light Box Maker or Cake Topper Maker already splits a design into parts, so you can assign silk to the visible one.
Is PLA food safe?
PLA is made from plant starch, and the plastic itself is used in food packaging. That does not make a 3D print food safe. A printed part has problems that the raw plastic doesn't:
- Layer lines trap food. The gaps between layers are tiny, can't be scrubbed clean and hold bacteria. This is the biggest problem.
- The nozzle may add metal. A standard brass nozzle can contain a small amount of lead, and it may carry traces of earlier filaments. Both can end up in the print.
- You often don't know what is in the colour. Pigments and additives are usually not listed, and silk PLA has the most.
- PLA softens at about 60 °C. A dishwasher, a kettle's steam or hot food warps it, and a warped part has more crevices.
So treat a print as a decoration or a tool that touches food briefly, not a plate, cup or bottle. You can lower the risk with these steps:
- Print with a stainless steel nozzle and clean it with a few purges of the filament you're using.
- Choose a filament whose maker says it's suitable for food contact, and keep that spool for food parts.
- Fewer layer lines mean fewer gaps. Use a thicker layer height, 100% infill and extra walls so no open pore reaches the inside.
- Seal the surface with a coating that states it is food safe once cured, such as an epoxy resin sold for that purpose. Follow its cure time. The coating fills the layer lines, and that is what makes the surface wipeable.
- Keep contact short, cold or dry, and not acidic. Cookie cutters, biscuit stamps and scoops for dry goods are reasonable. Cups, bottles, chopping boards and anything that holds liquid are not.
- Wash by hand in cool water, dry it completely and replace the part when it scratches or turns cloudy. Never use a dishwasher.
- Put a barrier between the print and the food. Cut cookie dough on baking paper, and line a printed tray with a food-safe liner.
PETG's raw plastic is also used in food packaging, and its smoother, glossier prints take a little more heat. It has the same layer-line problem, so the same steps apply.
Cake toppers
The stakes of a cake topper go into icing, so they are the part that matters. Wrap each stake in food-safe cling film or baking paper before it goes in, or use a food-grade skewer or straw for the part that goes into the cake and glue the printed topper to its top. Keep the printed part above the icing. Treat the topper as a keepsake, take it off before the cake is cut and wash it by hand. If you sell toppers, say they aren't for food contact. Rules on food-contact items differ by country, so check the ones where you sell before you advertise a print as food safe.
Filament for outdoors
Sun, heat, water and cold all work on a printed part, and PLA gives way first. It softens at about 60 °C, and a car in the sun can pass that, so a PLA part left there sags and bends. That's why the project box guide recommends PETG for a box that sits in a car or a shed. Three filaments suit outdoor use, and each trades something for what it offers.
| Filament | Outdoors | What printing it takes |
|---|---|---|
| PETG | Resists water, takes about 80 °C and bends under a knock where PLA cracks. Long sun exposure can fade it over time. | Prints on an open printer. Needs a nozzle near 230 to 250 °C and some care with stringing. |
| ASA | Takes about 95 to 100 °C and is made to keep its colour and strength in sunlight and rain. | Needs an enclosure, a hot bed and ventilation, and warps like ABS. |
| ABS | Takes about 100 °C and is tough and easy to sand. It yellows and turns brittle in sunlight unless painted or coated. | Needs an enclosure, a hot bed and ventilation, and warps. |
Colour matters with all three. A dark part in direct sun gets hotter than a light one, so a black part can pass its softening point on a day when a white one doesn't.
Printing ABS and ASA
ABS and ASA are made from similar plastics and print in nearly the same way. Both are tough, take more heat than PETG, sand well and can be smoothed with acetone vapour. They differ in sunlight. ASA is formulated to keep its colour and strength, while ABS yellows and turns brittle over time unless it is painted or coated. Both ask more of the printer and the room than PLA or PETG do:
- They shrink as they cool. Corners lift off the bed, and the bigger the part, the stronger the effect.
- They like a warm, closed chamber. An enclosure holds the part at an even temperature. A draught can split the layers of a tall part. Small, flat parts sometimes print without an enclosure, and a draught shield around an open printer helps.
- They print hot. Typical settings are 100 to 110 °C on the bed and 230 to 260 °C at the nozzle. Check your printer can reach both.
- They need help sticking. A glue stick, hairspray or an ABS slurry on the plate, and a brim on the part, keep the first layer down.
- They release fumes. Heated ABS and ASA give off styrene and ultrafine particles. Print in a ventilated room, ideally with the enclosure vented outside, and keep the printer out of the room you sleep or work in.
If a part needs more heat resistance than PETG gives, such as a mount near a heater or an engine bay, ABS or ASA is the step up. Print a small test piece first to learn how your printer behaves with it. If you have no enclosure and the part is for the sun and rain, PETG is easier to print and usually enough. If you have one, ASA is made for that job.
Tips that apply to every filament
- Keep filament dry. PETG absorbs moisture fastest, then PLA. Damp filament pops, strings and prints weak. Store spools in a sealed box with desiccant, and dry a spool in a filament dryer or a low oven if it crackles. Use the spool's data sheet for the temperature, because PLA warps in a hot oven.
- Print a test piece. A new brand or colour often needs a different temperature. Print a small tower before you commit to a long print.
- Stick to a few brands. Once you have settings that work for a PLA and a PETG, reuse the same spools. Doing so is quicker than tuning a new filament for each job.
- Use the right nozzle. A 0.4 mm brass nozzle is fine for PLA and PETG, apart from the food-contact point above. Glow-in-the-dark and carbon-filled filaments wear it out, so they need a hardened steel one.
Not sure the printer is up to it? The guide to choosing a 3D printer covers which printers print PLA and PETG well.
Questions
Which filament should I buy first?
PLA, then PETG. PLA is the easiest to print and suits lithophanes, name lights, cake toppers and most project boxes. PETG is tougher and takes more heat, so it suits hooks, clips, brackets and anything that goes outdoors or into a hot car.
Is silk PLA strong enough for functional parts?
No. Silk PLA is plain PLA with additives that give it a glossy sheen, and they weaken the bond between layers. A silk part can split along a layer line under a load that plain PLA carries. Use silk for decoration and plain PLA or PETG for hooks, clips, brackets and snap-fit lids.
Is PLA food safe?
The plastic is used in food packaging, but a 3D print is not food safe by default. Layer lines trap bacteria, a brass nozzle can add traces of lead, the colour additives are usually unlisted and PLA softens at about 60 °C, so it can't go in a dishwasher. Keep contact short and dry, print with a stainless steel nozzle, seal the surface with a coating that states it is food safe once cured, and wash by hand. Put baking paper or food wrap between a print and the food.
What filament should I use outdoors?
PETG, ASA and ABS all work. PETG resists water, takes about 80 °C and prints on an open printer. ASA and ABS take about 95 to 100 °C and need an enclosed printer. ASA keeps its colour and strength in sunlight, while ABS yellows and turns brittle unless painted or coated. Whichever you choose, a light colour stays cooler in the sun than a dark one.
What does it take to print ABS or ASA?
They are printed in nearly the same way. Both shrink as they cool, so they warp and can split unless the printer is enclosed and out of any draught. Typical settings are a bed at 100 to 110 °C and a nozzle at 230 to 260 °C, with glue or a brim for adhesion. Both give off styrene, so print in a ventilated room. In return you get more heat resistance than PETG, and ASA adds sunlight resistance.