HI, i`,m New, just joined but here`s how i made one earlier! I used two lengths of flattened silver solder, (Lead Free) approximately 4mm wide. Then I made a tapered sausage shape using a silicon gun and silicon sealant. I used a sheet of acetate, the type for overhead Projectors, slightly lubed with vaseline, to prevent the silicon sealant sticking to it. I ran several "Beads" of sealant with using the tube without a nozzle to get the biggest bead, so they were touching eachother. after a few minutes, a wetted finger helps smooth the beads and ensures they stick together. I left it to "go off" over night. Next day, I built up another layer of silicon beads on top of the first to get the diameter i wanted for a butt probe. Left it to "go off" again. I then used a sharp project knife blade to make slim channels along the length of the sausage, 1 channel on either side, and pressed the silver solder into each channel. Elastic bands hold them in place temporarily. Then using the silicone gun, I put a layer of silicone around each end to seal in the solder and ran some along each side lengthways again to hold the solder in place. I now have a sausage with a strip of silver solder running down the length, opposite sides to eachother, sealed in so no sharp edges. I soldered a red wire to 1 end of the silver solder, black wire to the other, and I have a bi polar butt probe! I just used more silicone applied with a wet finger to reinforce the soldered connections and shape the sausage and fitted connectors to the wires to attach to my electro pulse machine.
Hope u can follow all that!