This is pretty neat, if a bit useless for the average person. Instructables user MaskMarvl has put together a quick 7 step guide to making your own sugar cubes. Granted, it needs to use brown sugar so that it can stick together, but I’m sure you could eventually figure out the recipe for making your own white sugar cubes.
The whole process is actually quite easy and could probably be completed without the tools asked for, just two pieces of wood, and a drill. The sugar cube isn’t needed, make it whatever size you want, this is America after all.