I was doing my first non crumb tray work the other night and was super frustrated at it because I had to find junk around the house to work with and get it up the height. All the while cursing that my stuff for the CNC machine was at the shop and not my house.
Flash forward to today and after ordering another set online I stopped by the shop for my 123 blocks and my parallels set. I would highly recommend everyone pick up a cheap set of these (maybe $20 each? I ordered a high quality set to replace these cheap ones at the shop). It makes shimming pieces into the focus range so smooth and easy. Plus they are ground metal so they stick together when placed on each other and your magnets still work as a hold down. I will probably still grind a piece of CR steel to ~1.5 thick to avoid stacking, but that isn’t something everyone can do and isn’t really needed