This is my Terminal Box collection compatible with the very popular Plano Edge series of boxes. Designed from the ground up to complement their boxes, and offer sizes not otherwise available.  I've provided models for every option between 40mm (3 cells) and 130mm (9 cells).

I've personally used these in my Plano Edge 3600 boxes, and expect them to be compatible with the EDGE 3500, EDGE 3600 Terminal, EDGE 3700 Thin, and EDGE 3700 Terminal.

I recommend printing in PETG or ASA for anything to be used outdoors. I've been using Kingroon and BuMat brands of PETG, as their yellow is a very close match to the Plano color.

I've experimented a bit with printing translucent lids. It's not all that easy to accomplish with FDM printers, but if you're interested in this, I heartily recommend checking out TheIceBurge's PETG Glass Profile: https://makerworld.com/en/models/414482?from=search#profileId-316443

The lid can be secured in a number of ways. I have a bunch of 1.5mm Stainless welding wire on hand, so I've used that. It's a nice, snug fit and the lid works perfectly.

If that's not available to you, 16-gauge stainless wire nails should work beautifully.

In the worst case, a large paper clip will work, provided you bend the ends a little to prevent it from slipping out before clipping it to length.