I am looking for information on how to build a 115 Volt spotwelder for
sheetmetal projects.  I would like a schematic, and additional
information on how/where to obtain the parts, or how to make the
parts.

Ok, here we go, I didn't acutally think I would find anything on this,
but it seems more common that I would have figured.

Here is a site that gives all the info you requested, from schematic,
to parts lists, and a link to a site that sells the parts:
"Home-Brew Spot Welder"
http://www.5bears.com/welder.htm

Here is another site that shows how to build a Spot Welder based on
the "Home-Brew Spot Welder" from above but does a few things
differently.
"Build a Spot Welder At Home"
http://www.frii.com/~katana/spotweld.html

The only other site I could find with this type of information was
this Arc Welder page, which is quite verbose, so it may be of help.
"Homebuihttp://www.dansworkshop.com/Homebuilt%20arc%20welder.shtmllt
Arc welder"

Give that a shot, and if you have more questions please let me know.
Thanks,
--jld

OK, great!  Your a better searcher than me, thats for sure.  The
"Home-Brew Spot Welder" is exactly what I needed.  Thanks Again. 
Regards, Hotformer.