With a lot of work you could probably scratch-build a bridge that would work well using only hand tools but it would require some specialized metal working tools, a decent knowledge of metalworking and an awful lot of effort to make something that can easily be bought for fairly cheap and will already have a professionally plated finish. The effort would be reduced substantially if you have metalworking machines (mill, drill press, lathe) but you'd still need to consider some sort of plating when it's complete and you still need to know how to run those machines.I'm pretty sure my dad has a bottle of finish. Another question, should I make or buy a bridge? I was thinking about making a bridge myself but I don't really know how to start. It doesn't seem too hard but I just want to know what you guys usually do.
Rather than making your goal of building an instrument even harder by making extra work for yourself, I suggest you just buy a bridge. Used ones show up in the classified ads here on TB often and for good prices.