There's a lot to say about this whistle stand, but for generating STLs, the crucial knowledge is that it was designed using OpenSCAD with the BOSL2 library. The versions which this has been confirmed compatible are:
- OpenSCAD 2023.10.09 (git f41aefc37)
- BOSL2 (git 910c3ea7c0e25048913992eca7dcd2f37087c02c)
It may well render properly with other versions, but those are the ones I used.