Custom PC Hardware is a fan of MakerBeam. So much so he dedicated a video to our beams and how to use these for custom build PC cases.
Before he discovered MakerBeam, both regular 10x10mm and MakerBeamXL (15x15mm), he would look for a case to contain all the parts. Only to find himself searching for another case after he had upgraded or expanded his computer. All the parts of the new design would not fit the initial case.
With MakerBeam he dismantles the existing frame and reassembles it to meet his needs. As each build is a prototype, should the requirements change, the frame is easy to change too.