My Drive Rollator has a seat which pivots to allow access to a basket below.  It is attached by two clamps. One of the clamps broke and I wasn't able to find a replacement, so I designed this.

I printed this in ABS, but PLA should be fine.  I designed it with a custom removable support, and a washer to allow the clamp to be printed without supports.

The washer is optional, but if you want to use it print two.

I also proviided the Fusion 360 file if you want to re-mix or adapt.