Just get a Hitachi Magic Wand or Acuvibe with a dildo attachment. If it's too small just get a larger normal dildo and drill a hole in it that fits the current attachment then keep them connected with a condom. I assume that since you mentioned a "reciprocating" saw that you have enough mechanical knowledge to create something like that. I'd seriously look into smaller sizes with very specific shapes, however, since the majority of the sensation should come from your prostate there's no need to unnecessarily stretch other tissue with a large uniform girth rather than specifically targeted variable curves/thicknesses along the shaft. It's how ya use it right?
