Ironman build advice needed

I am going to build the Mech Test version of the suit (well gauntlet and forearm frame) and already have the pep files done. What I want to know is can I use just fibreglass resin and bondo on the gauntlet and fingers of do I have to use the fibreglass mat. The finger shells are quite small so using fibreglass mat on them would increase the thickness slightly.

This is my first build and first time using these materials so any help is welcome.

Advice needed.......

you could always use fiberglass tissue instead of the mat.