This 45 adapter is made from a printed base, a printed crystal, and an LED light from the Dollar Tree! Once you turn it on, you can watch the crystal rotate hypnotically when you play your records! (See the video below.) And when you aren't playing your records, you can stand it on a shelf where it will look cool.

Here's how it's made:

• Print baseforcrystals45adapter.stl in a dark, more opaque filament. (Mine is Prusament Galaxy Black.)
• Print crystalsfor45adapter.stl in a lighter filament. It doesn't have to be transparent or translucent – the crystal is pretty thin so the light will come through most light colored filament. (I used Prusament Vanilla White.)
• Get a cheap color-shifting LED light or nightlight. This is mine from the dollar store: 
   

• Take it apart. Depending on the light you get, you might have to trim a lot of plastic away (I did). But it won't be seen, so do what you have to do to make it fit :) It only cost $1.25 :)

• Put the light into the base.

• Then, put the crystal piece on top, and start spinning your discs! :)

NOTES:

I designed my own crystals but kept having PrusaSlicer telling me they needed supports, so finally I gave up and grabbed a crystal that was already known to print OK! :) Thanks, Arudinne! I made some small changes to make it work with the base I had already designed.

I found that the base prints a little sloppy inside, but that part is hidden while in use, so no worries there.

If you get an LED light that will fit properly, it can fit on the interior rim of the base with the crystal right on top of it. Mine does not fit quite that nicely, but I was able to put it inside the base, which also works.