It is possible to create inlays on 3D prints using a number of different methods.
3D printed inlay
It is possible to produce 3D printed inlay (multimaterial/multicolour printing on a small number of layers) using both:
- One hotend: mulitcolour printing with one hotend can be achieved both through filament changes in Slic3r and multimaterial upgrades e.g the multimaterial upgrade for the Prusa i3 MK2 and MK3 by Prusa Research.
- Multiple hotends: allow different colours or materials to be added by different nozzles.
Wax crayon inlay
Formlabs mechanical engineer Christian Reed has developed a method for creating colourful inlays on 3D prints using wax crayons.
ABS slurry inlay
Creating inlays using ABS slurry has a few benefits compared to wax crayons:
- Its hardwearing
- Its very cheap to create a lot of slurry
- 3D printing people are likely to already have acetone and ABS
- Its very easy to remove the ABS from areas of the print you don't want it to be using acetone on non ABS prints
- It sets quickly
- Its easy to get a good finish using a small bit of acetone on a cloth and sanding if wanted
- No equipment required
- You can mix filaments to make different colours
- Allows for the same post processing as normal prints.
And some downsides:
- Colours are limited to what you have in stock, buying a whole new roll of filament is not really practical or economic
- You need to do a few layers to get a good finish, as the acetone evaporates it shrinks, thick slurry means less layers
- ABS slurry takes a few hours to make
ABS slurry inlay is possible on many kinds of materials including PLA and ABS prints, it is easier to achieve on the top or (preferably) bottom of the print where there are no ridges to sand off post processing.
ABS slurry inlay is a lot easier on PLA prints, you can clean off excess slurry with acetone although the acetone can stain the PLA a little, but this can be avoided by being careful or sanding the print.
ABS prints bond very well but needs to be either sanded, scraped with a sharp knife or wiped with acetone to get it to a presentable state. Wiping excess using acetone works especially when the slurry hasn't fully hardened, but its easy to make the print soft if you're not careful. Scraping off excess ABS slurry is easiest before it completely set hard but still hard enough to cut.
- A thicker slurry is easier to apply and shrinks less when drying, but too thick and it won't get in all the corners.
- Deeper inlay tracks and much easier to apply slurry to and result in a stronger bond between the inlay and the print, this is more important to do when inlaying materials other than ABS.
- It is much easier to accurately mix different filament colours when already mixed as separate mixtures of slurry.
- When applying slurry to thin prints they can become more bendable. To help prevent this you can increasing the thickness of the slurry or reduce the amount of time you are applying the slurry either by quickly doing the whole thing or by doing it in sections allowing each section to dry in between.
Nail varnish inlay
Nail varnish inlay is very similar to ABS slurry inlay in that acetone is the solvent for both ABS and nail varnish.
The main benefits to using nail varnish as an inlay is that:
- It is available in a very wide range of colours and can include special materials like glitter
- It is very widely available
- It takes much longer to dry than ABS slurry, hours rather than minutes depending on the volume (mostly depth) of the inlay.
- It is relatively expensive to inlay a large volume
- Nail varnish shrinks a great deal when drying
- Several layers must be applied to achieve a flat inlay
- Some finishes can only be achieved through thicker layers eg transparent sections
- Thick layers dry very slowly (over 24 hours), more thinner layers is faster.
- Different layers of different colours or opacities can achieve different finishes eg a solid colour with a transparent layer with glitter in on top.
- A fordite like effect can be achieved by applying layers unevenly.