vettedreams ,
It just depends on how you want to go about it , and what type vehicle you are wanting flares for .
Many styles you can go with .

Stick with metal to metal , and glass to glass , as fiberglass doesnt bond very long to metal for any length of time ! The expansion and contraction of both materials are different and eventually cracking will occur.

If you are wanting metal flares , you can use 1/8"-1/4 " rod and form and tac weld it to the 1/4' s and fenders , then fill in with sheet metal , welding as you go .
Or make cardboard/ poster board paper templates then transfer patterns to sheet metal and weld to 1/4's and fenders .

With Fiberglass flares use cardboard templates and masking tape , then glass over the flares , then trim and bond to the glass , or wood templates , and glassing over them to make flares , then bond to vehicle .


SprayTech