These are magnetic LED fixtures designed for futuristic terrain. One is a single-LED fixture, and the other is a triple-LED fixture. The full instructions for assembly are at:

https://youtu.be/X8TmQnbpLTU

The 3-Volt coin cell holder with switch is from:
https://evandesigns.com/collections/wire-switch-more-v2/products/3v-coin-cell-holder-with-switch

The 3mm 3-volt LEDs are from:
https://evandesigns.com/collections/hobby-leds

The rare-earth disc magnets (0.375" diameter x 0.125") are from:
https://www.magcraft.com/magcraft-nsn0573

Here are the instructions contained in the video, should you wish to refer to them without watching the video:

The three pieces of each fixture are connected with sprues. Cut them apart with clippers and trim the nubs down with a hobby knife.

Prime the pieces. This will smooth out the surface texture a bit and will help with paint adhesion. I painted these with Citadel paints. The basecoat is Iron Warriors. I added rust and corrosion with Agrax Earthshade and Fuegan Orange. I then finished them off with a drybrush of Ironbreaker.

The fixtures are attached to the floors of terrain features with a rare earth disc magnet 3/8" in diameter and 1/8" thick. Glue the magnets into the handles with superglue.

Next, glue the 3-volt coin cell holder to the fixture with superglue. Allow the glue to set before moving to the next step. Apply superglue sparsely around the hole for the button switch. Insert the switch into the hole diagonally as shown, taking care not to get any glue on or around the actual button. Apply superglue to the inner edges of the LED holes and insert the 3mm LEDs. Allow the superglue to set before moving on to the next step.

Trim off any excess wire. Slip a one inch length of shrink tube onto one side of the red wire and one side of the black wire. Attach red to red and black to black. Use a lighter to shrink the shrink tube.

Bend the LED leads over at a 90 degree angle and pack the wires in the compartment as tightly as possible. Install the battery momentarily to ensure that the LEDs light up. If they do, use superglue to mount the compartment lid to the fixture.

Place the light fixture on walls or ceilings on your terrain by placing the magnet opposite the battery.