home-made tools

I recently overheated and pretty much blew up my jeep's engine. My husband knows quite a bit about cars and engines and so he's going to fix it to keep the cost of the repairs down. We're wondering if anybody knows how to make some of the tools neccesary for rebuilding a jeep engine as opposed to buying them. Anybody have any good tips on home-made tools or techniques for this kind of project? :D