Well I don't fall into the ranks of hot shot makers with qualtiy folders, but I guess I can share some of the experience I've gotten out of my on going attempts.
Books are good, but they won't teach you everything. At least for me, its much easier to learn by seeing things and doing things. I've learned a lot and am still learning from regrinding and making a new handle for an old delica. Taking it apart let me see exactly how everything fit up. I would strongly suggest you take apart an old folder you have thats of fairly good quality and study how it goes together. Or you can do like taz said and buy a kit. They however aren't very good from what I've seen, you'll learn more by playing with them and trying to make things fit up right with a little filing etc. than by looking at how they are as is.
As for tools, I'm struggling through with a hacksaw, a dremel, a set of small needle files, a 4x36 bench sander with a 6" disc and a worktable ( get a sqaure and make sure the table is as sqaure as possible when your using it to profile parts) a drill press,bits and taps, a woodworking bandsaw, and some other hand tools.
Now I really am struggling with just these tools. The locks aren't really the biggest part of the problem either(lockbacks). Filing them out by hand only takes patience and practice.
your alot better off if you have something like a bandsaw to cut out liners and things acurately, not to mention keep them flat. I cut out liners using the old million holes on the drill press and a hacksaw method and it worked, but it turns out that the liners got slightly bent and I may have to start over. Its important that everything is FLAT when you get to stacking peices. A qualtiy drill press is a must. The arbor on mine wobbles some and its hard to keep accurate placing for my holes. A center drill would probably help with that. Always center punch.
Get good drill bits, you want to cut holes through liners not punch them, that will also mess things up on fitting and you have to polish off that wire edge around the hole.
If your going to use screws, then a good set of taps is necessary. If your going to use pins then I would strongly suggest you have a lathe available to you. Extruded pinstock from the hardware store is not consistent in diameter. Try and buy good stuff if you can.
A milling machine would be nice but its not absolutely necessary, unless you want to make a business of making folders.In that case its not practical to file them out by hand. Hope that helps. Have fun.
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I may not be the sharpest knife in the drawer... but I've got the sharpest knife in the room.
