Modify crash racer track

I have a few questions 

has anyone modified the crash racer track pieces. 
Or can anyone help with advice on what glue to use etc. 

I want to mod a few pieces to suit my build but unsure on how to accomplish with out ruining the piece. 
I thinking of cut then brace underneath and use epoxy and some lightweight filler powder I've used when fibreglassing a boat transom back together... but I'm not sure about racing surface to make that neat and smooth and clean.