This is a wedge that screws to the bottom of your Moonlander keyboard so that you can tent it while still being able to tilt the thumb extension up.

For extra stability, you can't tilt the thumb cluster down anymore. My first iteration of this design allowed that, but I don't use it and prefer the extra stability of the keyboard with the extra material. You can press the outermost thumb key as hard as you like, and the keyboard doesn't move. If you have big hands, this is not the item for you (but you can slice off the part that prevents movement of the thumb cluster ;).

You will need to mirror this in your slicer to make one for the left hand.

Due to some measurement error, the holes do not quite line up, and you can only get two screws in. I measured the hole spacing as 19.5mm, but it's clearly not.