I've used plumbers epoxy putty in small beads. A lot of the builders for ghostbusters proton packs use it for weld lines on a couple of items. I did see lots of images on the ghostbusters forum when I built a pack. Worked great.
There's many way to make a weld (going down motion/going up motion) that makes for different "look" of the finish weld. I prefer a "going up weld" it looks better and the welding pros will tell you that it's a more solid weld also ...yeah, hot glue man, hot glue.
I've used epoxy sculpt with good results and even green stuff for small areas. Just used a rubber tipped sculpting tool to push it up onto itself over and over after applying.