Dont velcro man!! small tappers countersunk with do the trick, but remember this dude, mdf will bend due to heat or moisture. velcro with not do the trick. IMO you are better of using a masonite typr material that wont bend or you are waisting your time. I know from experience. In my old car, I made of some door frames with 4mm mdf and covered it with mirrored laminate, after a day of light sunshine it had bent out like a corn chip. go to reverse garbage in west end and get your self some masonite for like $3, if not there, any renovating seconhand kinda shop.