does anyone know how thick i need to make fiberglass for 3 10" type r's, also anyone know if amps will breath enough if i put a custom cut mirror in to make the top of the amps flush across to the t-top area where the 3 subs will be in a custom fiberglass enclosure.

 

Most fiberglass enlcosures I typically shoot for the 1/2" to 3/4" thick range; with those subs that should work fine.

As for covering the amps, if you are going to completely cover the amps, then add come fans to under the cover to bring in and blow out fresh air; otherwise you will most likely have thermal issues. This only applys if you are completely covering the amp, if the top surface is still exposed you should be ok.