So Im currently in works of designing a new airshroud and to be completely honest I have little exp working with bondo. I made a whole new piece to the shroud to cover the cpu and gpu heatsink and began to bondo but as I came to realize you can't just lap the bondo from one to the other and smooth it out after and make it stay together. It looked great when it was finished but I made one wrong move and dropped it and the whole new piece that was bondoed on completely came off with the bondo still extruding out looking like it was supposed to be attached to somthing :/. Sorry if this makes no sense its kinda hard to put into words well anyways I guess Im wondering how should I go about bondoing the two together? The new piece is made from plexi glass and the shroud plastic so should I wire the two together and leave a little gap to let the bondo get between them and then work on making the entire mold around the plexi ( for looks )? Idk Im really struggling here and input would be helpfull.

I am sure if you took some pictures we could help you better

Bondo isnt very strong.. honestly. Not for something to be made SOLID out of it... but, I do know there are fiberglass sheets and resin that bondo makes for it, which would be much stronger if you did a layer over what you have now.

I would post pics but sadly my camera came to an end...I forgot it in my pocket and it went through the wash ugh. O well thx for the replies Ill look into the fiberglass.