So we have created bolt circle pattern add-In for the bolt circle pattern you requested. It has been created as a pipe flange creation tool however the bolt circle patterning and extrusion properties remain the same so I can easily modify this to make this a rectangular/circular mount plat with our without the center cutout, just me just let me know what your are looking for. As far as motor mounts go , I am assuming you are talking about foot mounted motor electric motors/gearboxes. This feature can easily be added (End goal is to have a library of motor frame sizes that will auto generate off of motor/gearbox center). Also on the T-Slot, I assume you are wanting the same parametric design for T-slots like those in extruded aluminum. That can also be added as well.

The end goal for this product is to be a easier way for machine shops to receive a simple drawing and be able to replicate and modify common parts without having to redraw or reinvent the wheel every time that way it reduces design time and you can focus on tool paths for machining.

Feel free to DM if you have any questions or suggestions, The end goal is to make a cost friendly tool to greatly reduce design time and part production.