The place that should have it is
Graphite Elegance.
Their site has been down for a while, though.
There are other materials that would work. Like 8542K11 (3/16" thick fiberglass with 1 1/2" long legs) from
McMaster-Carr.
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
4wd 4-link rear/IFS Pro4 truck,
Custom Hyper 10 Short Course,
Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz