Here's one I have mentioned only once and that was a long time ago.
Say you are thinking about these things, P.E., a Paper Model, A Wood Model or something with a lot of flat thin metal components! And Yes! Plastic too ( Scratch Built!).
There's something we need to know as well as Gluing, Painting and Modifying as well. It's shaping basic components into the parts we need to finish the parts or details. The process is simpler than you think. In wood it works well if you wet the wood , shape it on a jig, then let it dry. It will take shape as it dries and make your work easier. Never think for a moment you just do this and it's done. You still have to make the part fit.
When you shape there's methods you can use that have been used for many centuries for just that. Rolling ( using a Dull side of a knife or the edge of a ruler) Curving like a bowl or dome. This on takes another idea that works. With wood and paper it's the same in many ways. In Wood, heat is used too ( Mainly Steam). With paper it's a very fine mist on the paper. Then a craft sponge and a Spoon or other Device to press the damp paper into for shaping, and time to dry.
This assumes that you have taken art classes in basic grade school and know what a Cone , Cube, and Sphere and Folds are! These are the mostly needed shapes you deal with.
Always keep a tool for creasing the paper ON the line as drawn. Nope, not next to the line. But, Right on it. This is important for hiding the printed lines on a paper model and making sure metal or plastic parts fit well! Make Sure this tool can crease sharply WITHOUT cutting through the paper or thin plastic. With thin plastic it helps if the plastic is done with multiple sweeps of the tool.