Thanks Jeff!
I saw I’m not the first with an Ikea table. I love @2mas ‘s result too. Perhaps my next build 
The table has 54cm outer diameter (21"). The useful diameter for the patterns will be 340mm (approx. 13’’), once I optimize the design.
Regarding the homing sensors: I really wanted to use something relying on magnetics rather than taking an optic or tactile sensor. The problem is, I would not currently be able to differentiate if a hall sensor was triggered by the “rho” homing magnet or the “theta” homing magnet. If I have two sensors for theta that need to be triggered simultaneously, I can tell them apart.
This is one place where you all you might have better + simpler ideas 
You’ll notice I’m not a software-specialist. So any input when you’re looking at the code is greatly appreciated 