Markforged 150cc Fiberglass CFF SpoolMarkforged 150cc fiberglass spool Fiberglass is Markforged's entry level continuous fiber, providing high strength at an accessible price. Parts with inlaid continuous fiberglass are setting benchmarks in the market and, through a patent, only possible on Markforged systems. 2. 5 times stronger and eight times stiffer than Onyx, Fiberglass reinforcement results in strong, robust parts with excellent strength to weight ratios.