The two carriage hold-downs shown above could not be so handy out of the knurled thumb knob ending a 75 mm (3 inches) threaded rod. The three-lobe knob allows any thickness up to 35 mm (1.5 ") to be clamped on the sliding table and is merly a stack of crossed ply. One of the two thicker plies holds a square nut.

Here is one way of making clamping knobs from stock left in the shop. I had some blocks of oak flooring I took in pieces and resawed some elements into thin sheets then stuck taking care of crossing the grain and cut in four squares before drilling the centre hole. I bored half of them so that accommodating a square nut and got two parallel faces with the help of the sanding disk on the spindle moulder. I stuck another crossed veneer layer to make an embedded nut into five plies.

The saw feeder but also the mitre gauge on the sliding table right to the blade were powerful to safely saw the small delta shapes. It remained to form the three lobes with the sanding drum. You may find out the ring fence modification reading that paper and the see-through over guard details in this document.