Reddit reviews Abacus Mind Math Instruction Book Level 1: Step by Step Guide to Excel at Mind Math with Soroban, a Japanese Abacus (Volume 1)
We found 1 Reddit comments about Abacus Mind Math Instruction Book Level 1: Step by Step Guide to Excel at Mind Math with Soroban, a Japanese Abacus (Volume 1). Here are the top ones, ranked by their Reddit score.
Even low-end soroban suit my needs (and I'm pretty picky about having good tools). I think I have a few that are around this quality: https://www.amazon.com/Flexzion-Arithmetic-Calculating-Oriental-Calculator/dp/B018SA829E
The only bad experience I've had is with some of the wooden abacuses being low quality and splintering on the back. For a younger child, I might just want to go plastic.
To teach younger kids, I recommend the SAI Speed Academy's series: https://www.amazon.com/Abacus-Mind-Math-Instruction-Level/dp/1941589006
I don't know about other bases and the soroban, though. Sorry!