Printed in orange PETG, 90 infill, support touching build plate, .28mm layer height, rested on flat back of hex recess, visible faces pointing up. To install: Carefully position the recess on the cooler exterior, mark the external edges of the recess onto the cooler exterior with a sharpie or something. Cut the cooler exterior wall and remove internal insulation to make room for the recess to lie against the exterior cooler wall. I used a Dremel tool with a 199 bit (looks like a little metal circular saw blade) and it cut the plastic exterior just great. I used a fresh Xacto #11 blade (in a knife handle, of course) to cut the insulation out. Quick. Keep a vacuum around for that insulation. Once you've positioned and cut out for the recess, mark and drill the 28mm hole through the insulation and interior wall at the drain plug boss. I recommend you use a bead of RTV silicone around the exterior wall hole, to keep spilled drain water from soaking into the insulation and growing bacteria in there. The drain plug does all of the interior sealing with its rubber washer against the interior wall, and snugged up, the rubber expands against the drain plug shaft. The silicone only prevents exterior water (spills, rain, washing with the hose, etc.) from getting into the insulation and growing nasty stuff. Do a test fit and assembly before adding silicone. Really: do a test fit and assembly. After you've laid the silicone bead, insert the recess, then thread the drain plug through (hex end to the exterior side, threaded end to the interior). On the interior side, proceeding from the cooler wall place the rubber washer so it sits around the shaft and IN the wall hole, then the plastic washer (recessed interior area toward the rubber washer) then the plastic hex nut. Tighten it well so the rubber washer can seal against both the wall and the shaft. If you use a wrench, the interior nut is about 1-1/8 inch. Make it good and hand-tight, but not so tight you de-laminate your printed part. The recess sides are 3mm thick, which is pretty good, but the plug force goes through the weakest axis. For easy cap removal and replacement, you'll need to trim the cap leash off the cap (and discard the leash). This means you'll have to keep track of the cap. They didn't put a leash on there by accident.