I have my tricks for this kind of thing, but indeed sanitation is a primary design consideration if I ever were to go down this path. My fab skills are up to snuff but my sw skills need much more work.

I don’t consider printing to be my only medium as a maker. I spent most of my 20’s painting cars, airbrushing graphics, and dabbling in composite prototyping over clay. Printing is just a convenience now because I’m physically limited.

With the right techniques it is possible to polish ABS in particular. If polishing is used as the primary surface finish technique, and only a very brief wipe of a diluted acetone is used over this surface, it is not hard to make a long term water tight surface. My experience plays a major role in what I call “not hard” but suffice to say, the golden rules of automotive paint are: 1) Paint is 99.9% sanding and prep work and 0.01% actual painting. And 2) When you’ve spent forever sanding something and think you should be done, take a break, come back, and acknowledge you are only half way done. Repeat this until it’s perfect. The hardest part of learning to paint at automotive quality levels is defeating yourself and your inner expectations about time and work. So “not hard” is in this context.

I’ve done many tests with various techniques when it comes to ABS. After polishing and light smoothing the surface is altered through the first 1.5-2 millimeters depth. The part designs for this finishing technique are quite challenging though. You need good mechanical access to all of the parts surfaces that need polishing, and when it comes to ABS, unless you have a temp controlled Voron 2.4, the layer thickness transitions in the print are quite critical to prevent layer separation even with an ideal sealed passive enclosure. Absolutely any bed movement is a problem on larger part designs

I made a small printed sheetmetal stamping press that can handle ~100mm^2 sheets. I could use that for structure, or parts of an Erector set, which would be humorous. The best solution would likely be a set of printed molds for food safe silicone. I also have some 2 part plastic for casting, plaster, and a few meters of a 2k twill weave CF laying on the shelf begging for a project.

I’m a mod of 3D Printing at the world BTW ;)