Cascade Film Holder

I have a few Photobackpacker's very useful cascading film holder and would like to add more in different sizes - and realised that it went out of business for quite some time already...is there any similar products that are still offered on the market or am I stuck with finding used stuff?

I generally liked Photobackpacker's products for their thoughtfulness. One wonders if they have a successor now that there's a surge of market interest in large format stuff.

Daniel Stone is making something similar. https://www.stonephotogear.com

Thanks - they look a bit like the Gnass design. Let me check if they also do other sizes.