I just made a eHERMS keggle using weldless fittings for my brewery...there are a few places with how to's but none of them were exactly what I wanted. I'll post some pics when I get home, but I basically used one od the 1" NPS nuts with a silicone o-ring for the element, 25' copper coil (3/8") and used compression fittings that have a male 1/2" NPT end. I soldered a washer to the fitting right above the threads where it seated against the hex portion. Then used a flas silicone gasket between the washer and keg wall to make the seal. Works great, and I can thread on whatever valve/coupling I want to the outside threads. I am using a bottom drain setup with a 2" sanitary coupler and a regular weldless bulkhead and valve for the water in/ recirculation return.