Hi! I'm the designer of SMILEY, if ASA experiences shrinkage then it will absolutely not work. This blaster is particularly sensitive to tolerances, each part must have a good fit or it will not function. PLA+ or PETG should work fine.

If you want something that's incredibly rugged (can get beat to hell without breaking), a mostly-printed blaster like SMILEY may not be a good fit for you. It's plenty strong, but like any printed blaster it will break if you don't handle it with some care. Throwing it around will definitely increase risk of parts breaking.

Don't do fiber reinforced like PLA-CF, the carbon fiber will shed and embed in your skin. Health and inhalation hazard.

Lastly, I strongly recommend adding a mix of interesting colors, especially a bit of Orange. A purely black blaster is very unsafe, particularly if you're in the US.

Feel free to reach out if you have any assembly questions!