KevVader wrote:
Still not sure if that makes sense....taking a mold of the inside would lose all the exterior details.....no? Especially on the bumpy cap helmets...all the paint drips, bumps, etc....
I don't think that in vacuum forming the plastic sheet is going to pick up
that much detail. The detail you see depends on how much the plastic sheet is able to bend and wrap around the template's shapes and structures. Its own thickness will govern how it will appear; the thicker the plastic the less detail there will be on the outside, and conversely the thinner the plastic the sharper the detail.
Assuming that the plastic sheet is completely accurate in its forming, there is a good chance the underside's negative shape is very close to the object's positive shape. By virtue of the thickness and nature of the material, you may end up losing some sharpness of detail.
But if you cast the inside of an already formed helmet, there is a chance for you to make up for the lacking detail by working on the newly cast inside.