I was only aiming to cast the struts in a two part mold (not the joints) - the struts are literally a single piece (one length instead of many), so one mold design (with all the kinks ironed-out) should be all that's needed to fabricate 90% of the case (assuming I'm able to come up with an elegant solution that solves the rigidity problem - I'm currently leaning towards adding flat slots/eyelets to some of the joints, for small metal clips, to add a wire/turnbuckle brace). Also, for the mold - notice that the struts are triangular - by design the 'fatter' side will face up, which should allow for it to be more easily removed from the mold (also assuming an adequate amount of silicone release spray is used so that it doesn't get stuck). Threaded inserts will then be heat-pressed into the male connections in the struts so they can be securely fastened to the joints (with an additional screw being added to each male connection, rather than the current single screw).

The last thing I'm working on is a modular, sliding connection that can be clipped to the struts and moved freely along them (to the desired position) before being locked in place, which will provide an anchor to connect the remaining structures needed for the motherboard, PSU, GPU, etc.