Reinforced speedmod gantry for Rook Mk1

Remixed the gantry from Gulsifer's speedmod to have more reinforcement all around to increase the stiffness when printed in lightweight materials (this was designed to be printed in lightweight ASA). For me, this is stiffer and lighter than the original part. Requires 2 x ~200mm long 3mm outer diameter carbon fiber tubes Cut carbon fiber tubes down to length, and glue them into the holes along the top and bottom of the gantry using a strong 2 part epoxy resin adhesive. Be careful not to leave a piece of rod occupying space that will be requred for the bearing. You will probably need to gentrly ream the rod paths through the carriages with a 3mm twist drill bit. Add shims (if required) from something that doesnt deform such as aluminium foil between the downward-facing pieces and the sides of each MGN9 carriage for a firm registration.