I've not seen anyone try, but it would seem to be a worthy project to homebrew a loop tuner box. The MFJ-936B and its brethern may be fine units, but it's main drawback is the capacitor range in pF and its power handling capability. A wider tuning vacuum-variable capacitor is one way around this. But they aren't cheap. I already have the main $$ item--a Soviet surplus vacuum variable capacitor 5-100pF with a 25kV rating (twenty five!). So in some ways I'm halfway there. Putting it in a box gives me the ability to use a turns counter and be able to make SWR adjustments on the box instead of on the rig. I could also dial it in and put it in the yard, and run higher wattages without having RF exposure issues. Looking at the MFJ box, its a bit unclear to me why there appear to be two air-variables (not sure what the smaller one is). One is for TUNING and the other is MATCHING. After that, it has a wattmeter, SWR meter, and some nice touches to it. A frequent complaint about it is the location of the coax input. Well, can we do better? I'm game for building one if someone could explain what would be involved in terms of that second air-variable. I'm assuming its not an inductor since I don't see the roller on it--but its a bit hard to tell. Supposedly the loop antenna is the inductor, so for matching purposes, I'm not sure what I am looking at. A lot of guys just adjust the SWR on their rig, tune for their point of interest, and never fool with these things. Overall the cost wouldn't be a lot less than buying one with a warranty, etc, but it would have decent coverage, lower losses, and QRO capability. Buy a higher pF rated VVC and you can run any band you want, even 160, if your budget allows it.