Quad Arm Material
Description: 4mm x 20mm 1000mm - PULTRUDED-Flat Carbon Fiber Bar or Strip.
Source(s): Carbon Kevlar Supply
Alternate source: Dragonplate
The 1000mm piece will be cut into two 400mm lengths for quad arms and two 70mm lengths which are used as backing plates when bolting the arms to the fuselage. details
If available, it's probably OK to use a thinner 3mm strip.
The Mozzie used a smaller pultruded carbon fiber strip (3mm x 15mm), plus 3d prints for attaching mounts, plus 3d prints to attach the arms to the fuselage.