We recommend printing with the material that you’re familiar with. If you are about to purchase a printer, definitely go for PLA filament. If you’re more experienced, and you’re familiar with printing with e.g. ABS, you can print the modules with ABS. This will make the box/modules even sturdier.
From our experience – don’t buy the cheapest filaments on the market, as the quality can be very low. We recommend authentic brands, such as Ender, Prusa, etc.
Please, avoid using no-name Chinese filaments. We can’t guarantee the result with random materials, we’re sorry.