The Rhymestone is a 40 key ortho split in a 5x4 layout. I got mine from Boardsource. This is a simple enough build and mostly standard. The board supports both through-hole and SMD diodes and uses Kailh hotswap sockets. Boardsource doesn’t link to the original author’s build guide so here it is. Google Translate or similar is required if you do not read Japanese.
There’s only one part of this build that gives me pause. Specifically, the per-switch LEDs are very old school and a style I generally refuse to deal with. Take a look at the photo below from the build guide.
This is a very old school sway to installing LEDs from before the existence of the SK6812-E LEDs that just lay flat in the hole with legs that hold things in place. For the Rhymestone and similarly older style boards, the idea is that you put tape on one side of the hole, gently lay the LED in the hole, and solder a bridge from the PCB pad to the LED. If this seems wildly problematic and fragile to you, we are of the same mind.
Otherwise, this is an easy build that yields a decent 5x4 split ortho. The board is also open source, under the MIT license, if you’d like to order your own from JLCPCB or AllPCB or wherever instead of giving money to Boardsource.