Thingiverse seems to be fubar'd, still doesn't show that listing. Even for me (shows I have x designs but only x-1 are displayed). So, here's what I entered:
Eggtracker Mini (only tested with Rev C3)
Turnigy Nano-Tech Plus 300mAh 2s 70C Lipo Pack (hobbyking, amazon, search around and try not to get raped on shipping)
2 2mm threaded inserts
https://www.amazon.com/gp/product/B09MCWX6VV
4 3mm threaded inserts
https://www.amazon.com/gp/product/B087NBYF65
2 m2 x 4mm machine screws
4 m3 x 12mm machine screws
2-56 7/16" nylon screw, McMaster part number 94735A711
2-26 nylon nut, McMaster part number 94812A100
1 SS-5GL switch
https://www.digikey.com/en/products/detail/omron-electronics-inc-emc-div/SS-5GL/272367
a 2mm rod, bicycle spokes work well (bet your local bike shop can give you a few used ones). Sand the end round to ease insertion.
Printing:
I used a Prusa Mk3s and Atomic Filament orange PETG at 0.2mm layer height, 2 perimeters, 3 top/bottom layers, at least 25% infill (the attachment loop is the only place there is much infill and you want it strong).
PETG strongly recommended. Polypropylene would be optimal for strength and minimal weight. Probably avoid CF blends in case of any RF attenuation.
Print the upper and lower with the bolt holes down, you should be able to bridge the outside of the case.
You'll need supports only under the tab in the lower that keeps the battery from sliding.
Assembly:
Install threaded inserts (3mm in lower case, 2mm on bottom of sled) by pushing in with a soldering iron set at about 200C, or as low as you can go if you don't have a temp readout.
Assemble eggtracker normally, do not attach power leads yet. The 3 programming pins may need to be bent down a little so they don't stand any higher than the GPS chip. Or just remove them once you've programmed your frequency.
Remove lever/sail from SS-5GL switch by pulling off with a pair of pliers. Cut off center (NO) lead.
Attach switch with nylon screws. Terminals should point up towards where eggtracker mounts. Optional dab of CA or melt threads with soldering iron so they never come undone.
Tape battery temporarily to bottom of sled in it's approximate final position. Feed power lead up through the square hole in the sled.
Cut the ground (black) wire off the back of the battery's 2-wire power connector at the base of the connector. Cut ground to length and solder directly to eggtracker.
Now cut positive wire off the same way, then cut positive to length to reach one switch terminal (don't solder yet, it would be a live connection at this point). Use the cut off portion to solder from the other switch terminal to the eggtracker (now).
Fasten eggtracker with 2mm screws. The screws are smaller than the ET holes so you have some wiggle room to get a perfect alignment before tightening. Remove battery tape.
Put the battery in the lower compartment and feed the charge lead through the slot so it stays outside. Try to keep wiring clear of the rod and switch. A drop of glue to help retain wiring if needed.
Screw the sled to the lower temporarily so you can insert the rod and keep the switch "off". Now solder positive battery lead to other switch terminal.
Pull rod and verify operation, verify that it goes off again when rod re-inserted and stays off through normal handling/jiggling in your field box.
Remove screws from the lower. Install upper over the antenna first and then seat it down over everything.
Install 4mm screws.
Optionally wick some CA in between the seams of the loop (you'll then need to print another case if you need to open it again). You could also CA or hot glue down the charge lead if desired but there's not enough slack for it to go anywhere.
Suggest you use sharpie to write down your frequency and contact info if found on the case (or edit and deboss your name in it like I did).
You'll probably need an extension for the charge lead, depending on your charger design.
Pin handle is optional, designed to glue around a bicycle spoke and has a hole for lanyard/remove before flight tag.
Another option is to drill a small hole above the eggtracker LED, but you'll lose some water resistance.
To use, fold shock cord and push fold through loop. Pull the shock cord folded loop up over the antenna and back down the other side. A little tape on the knot if you're extra paranoid.
Pull rod, verify reception, and go fly!
Turn the transmitter off with the pin before charging the battery. It would see a little more than the normal battery voltage and I'm not sure how well it would handle it.
