This a Gridfinity bin designed to hold an HT-174 and HT-100 set of rivet clinchers from Hansen Rivet.
There's also a couple spots for addition clincher dies for the HT-100.
I hacked this together in Tinkercad. If you wish to modify it, check it out there: https://www.tinkercad.com/things/0lKXjuNaRns
The original base STL this was built upon was made courtesy of the gridfinity-rebuilt-openscad project. And of course, original concept by Zack Freedman.
The author marked this model as their own original creation.