I have a thing that I'm building for my dad that's still in progress: a battery powered practice amp. I got a cheap SS amp from Monoprice just for the cabinet. I replaced the speaker with a Jensen C8R and replaced the black grill cloth with some Oxblood stuff that was on sale at Mojotone. The circuit is the Runoffgroove Professor Tweed, going into a little 2.5W class D amp as a power section. I designed and 3d printed a bit to hold 6x AAs for power. What's mostly left here is to make a new metal enclosure to hold all the electronics. I'm still struggling with figuring out how to cleanly cut my aluminum sheet to size. Then it goes into the cheapy Harbor Freight metal brake to bend it into a box.
