If this were a machine built by a hobbiest on here I'd be saying good effort and well done. But I don't understand the choices they made if they have been doing this for so long; which also would be missed by a novice customer.

Local drivers right next to the motors is odd - yes the cable run to the motor is short, but the signal cable from the PC is very long. Surely not good for interference? They are also going to get covered in dust, or metal chips which will drop into/around the connectors and with a bit of luck short the power supply.

Large high torque motors usually need lots of volts - I missed the power spec but the supplies looked like generic ebay ones which I've seen up to 60V. Has he fallen into the same old trap?

Bike chain? Ballscrews are not that expensive and give good repeatable results.

Gantry stiffness - looked like an open channel with thin walls which might be OK for foam, plus softwoods, but the gantry width he was talking about seemed pretty wide for such a lightweight structure.