Reference

Before I began I need to gather a ton of reference to make sure I get the right look.

The Fallout Wikia has a great page all about vaultsuits.

For the purpose of authenticity I fired up the G.E.C.K. to take a look at the in-game models.

There are about five different flavours of jumpsuit (vanilla, armoured, tech, security, etc...); I figured if I made the standard version I would be able to mod it later.

Using the Fallout 3 Archive Utility I ripped the texture from the main archive...

Using this image I was able to construct a fairly accurate blueprint of the belt and other detailing...