Bald caps can be made from plastic or latex, they can be made to measure by using cling film to mark the head shape and hairline, then place this on a ”red head” mark out hairline again using chalk or white eye pencil and dab on layers of latex.
In order to disguise the hair you can pin curl it and pin down, making sure to hide the clips so they dont puncture the bald cap itself. We made latex bald caps in college and discovered that the main thing to remember is to have very thin outer edges so they are easier to blend as nothing can melt/dissolve latex you see whereas Plastec is dissolved and blended away using acetone.
Below I have a couple of pictures of bald caps i have made/used. The lizard looking girl is wearing the latex bald cap i made to measure for her head specifically.
I also used a latex cap to copy an image of one of the nasty characters from the movie ”Sin City” his name was : yellow bastard (The first picture is from the actual movie, the rest are my try at it!)
I used a plastic bald cap to transform my beautiful mother into a freak show bearded lady!! 🙂