I use FreeCAD and OpenSCAD to design around existing COTS such as PVC pipes, hardware cloth, steel plates and such. I use more COTS to join and strengthen the segments such as fencing wire or even mortars and cement. I experiment with building caterpillar tracks and conveyors, to collect and optimize CAD data about them.

In decade or so, just before I retire, I am going to create a local maker association, where we sell the contraptions we build, and use the funds to build and maintain a local "data center".

Its a plan which is not entirely terrible. Thanks for asking.