If you want to make your own tube guitar amp, especially one that you can play at reasonable volume and still get a good sound (which is a common problem with most guitar amps, they only sound good when played really loud), then it can't hurt to go to the AX84 website. They have several basically open source tube guitar amp designs, many of which are designed to sound good at lower volumes. They also sell kits, but you don't need to buy a kit to make an amp, just scrounge around for parts and there you go...