*waves*
I totally understand where you're coming from. That's exactly why I built it.
In short, I added sump heaters to my plane at the last annual and, like your friend, after looking at the available options was disappointed. I knew I could build a much better one and it went from an "I'll build one for myself" to something of an obsession to see how nice of a box I could actually build.
The board was designed to IEC 60950 and the enclosing Box to UL 498A. The box is custom injection molded poly-carbonate. The PCB is a single board that switches only the positive leg. HV and LV are isolated from each other with no connecting copper and more than 10x the required clearance. The power leg for output has a 15A thermally sensitive slow blow fuse, a surge protector (MOV), a safety capacitor, and each of the relays is rated to 16A. The power for the radio has a 0.5A fast blow and a common mode choke for noise filtering. The neutral and ground are tied with Wall-Nuts (NEC compliant). The cords are all 14 gauge and are UL listed.
The power trace is 10mm total on the outside layers of the board. At 12 amps continuous, it will heat up 10C above ambient. At 15 amps, 15C.
It'll pass UL, but my CPA spouse was already going to wring my neck after the bill came for the injection mold tooling and first run of PCBs for my "little project".
By cost, it's 76% US made. The Printed Circuit Board is made and assembled in Lenexa, KS, final assembly happens in Overland Park, KS and I personally program and test every unit before it goes in the box.
The service is $50/yr because I have a decently large business relationship with Verizon.
I have a day-job reverse engineering electronics, so I enlisted James here to handle the sales aspects.