Fun because it's so flexible
Step 1: LED Tag, Badge With Many Uses
Here is a super low cost LED tag that can teach basic polarity (+ & -) of DC power while creating something that you can customize on the fly.
Corrugated cardboard is really useful for these projects and it's everywhere. The one I'm using here is a double ply from the liquor store, so it's stronger and thicker than the regular 1/8" grocery box cardboard.
The 4 pin Piranha LED has 2 contacts for each pole (2+ & 2-) The pins will poke into the cardboard like thumbtacks.
The 2 + pins remain exposed in the battery cut-out. The (+) edge of the battery will contact them.
The (-) side of the battery contacts the copper foil tape, which wraps around to the other side of the badge to make contact with the other 2 (-) pins.
Step 2: Diffuser and Artworks
I have used some packing foam (styrene) to diffuse the light. Favorite logo or picture printed on white paper or stenciled on a Styrofoam shape.
Its all stuck together with transfer adhesive (very thin 2-sided industrial tape) , permanent glue dots will work also.
The 1/4" wide conductive copper tape is normally used for stained glass and is easy to solder the LED contacts to. It will work for many LEDs strung together also.
A thumbtack is a good tool for starting the holes for mounting the Piranha LEDs. Also can pin your tags to surfaces.
If the battery is mounted loosely, it give a flickering, flashing effect when it moves.
The cardboard could be coated with resin or epoxy if you want the battery to 'lock' in.
The (+) pins will protrude through the back of the tag and interfere with the conductor (could cause a short)
They could be bent, cut shorter or have an insulator to cover them where the copper tape crosses them.
These seem to stay bright for a few days and still glow a bit after 2 weeks.