Dave, First off, I'm terribly sorry I haven't responded before this; my server is undergoing a switch over and it has any pictures of scratch made seatbelts on it that I have. I was told (and hoping) that it would be back up yesterday so I was stalling, but alas, I have accepted that that is not going to happen. They're are probably others who do a much better job than I do, but essentially I take the foil and for the shoulder part of the harness, I make two sections (out of the foil) - a very top part and a lower part joined with a solder (smallest size found at radio shack) buckle. Then at the bottom I try to make something that somewhat resembles the actual buckle again with solder - I usually actually look at a pe set of belts to try to get as close to shapes as I can. Then I make the lap belts - one piece, with buckles. After that I paint and use a very sharp mechanical pencil to try to give some detail, stiching, etc.
As for guns, I also don't really like what is usually molded and do cut them out and make me own (I did this on my last wildcat too :-) ). For the replacement, I use different sizes of hypodermic needles. I'm not sure where you live, but here in WA, I can get them at the local drug stores. I usually just explain what I am using it for and other than the random strange looks I have no problem obtaining them there. I think some places / states don't give needles out so freely. I also have a box of 100 or so that my vet (a parent of one of my students) gave me when he found out I was a modeler - they tend to poke animals with bigger needles than people so they are a pretty good size. Also, I have a book with a great, couple page tutorial on using the hypodermic needles as gun barrels if you would like I can scan and send.
Anyway, hope any of this helps. Keep us posted as to your progress. and let us know if there is anything we can do to help - you lucked out and there are quite a few good builders in this GB - way better than me atleast ;-).
Leon