Building the circuits onto breadboard is a very useful exercise but I want a permanent solution, so I designed PCBs to meet that need. I designed it so that each section of the computer is a separate PCB, so that the computer can be modular. The advantage of this is that if I make any improvements, it only affects one circuit and a new PCB can be designed. Also, I have made my PCBs available for purchase at my Tindie store. You can buy one or as many of these circuits that you want from here:

power supply

clock module