Dear Stefan,
Regarding transparency of transparent resin parts, please check following article in our help center: https://imaterialise.helpjuice.com/materials/level-of-transparency
Standard model-making paints (e.g. Revell) work great with polyamide (SLS), mammoth resin, standard resin, gray resin and high-detail resin. Both acrylic and water-based paints work as well, but several layers may be needed. You can use a primer first to smoothen the surface of your model.
Tapping of screw threads can damage resin parts or produce heat can deform them. Result will depend on the design of your part and tools that you are using. Please remember that screwing and unscrewing in a plastic material will only work a few times.
The best alternative to tapping a thread is to use metal threaded inserts. By doing this, you can use the connection multiple times and chances of damaging the model are much lower. Choose the desired thread size, look up the corresponding insert dimensions and foresee a blind hole of the correct dimensions in your 3D model. Also be sure to foresee enough wall thickness around the blind hole (min. 2 mm). We recommend using self-cutting inserts.
Polyamide can be compared to other plastics. Here you can find technical specifications of polyamide (SLS): https://i.materialise.com/en/3d-printing-materials/polyamide/technical-specifications
