One alternative is to transfer the contents of one of my old computers into a ATX Mini-tower.o
Pictures of a full ATX MB in a mini ATX tower case. (see bottom) Cable management may take some special consideration, possibly wrapping the PSU cables may help.
Requirements:
A full ATX MB fits it (some require micro-ATX MBs)
300W. Power supplies are usually underated, so add a little more.
Max 15.3" (388mm) high, though 14.x" would be nice.