Handy small parts dog is a hex nut with three threaded hole for screws (SHCS) to be the driver.
My favorite quick and dirty is two near-identical bars. Lets use 3/4" square mild steel and 2" workpiece on a 10" swing lathe as an example.
The basic concept is to clamp the two bars side-by-side, drill a hole about 1/3 off one end. Hole needs to be half into each bar, and of lesser diameter than the work piece.
Now reverse the notched bars, aligning on that first drilled hole. Clamp, drill, optionally tap (but nuts will do, too..) for two bolts, one either side of that hole that can draw the bars together.
At least one more hole will be wanted at the other end to provide for bolt, shoulder bolt, or pin to engage a dog-driver plate slot ELSE rest against a chuck jaw.
The edges of the undersized hole will contact the workpiece in four places. Make the semi-circles a vee if you wish.
Pretty quick to make, average tools, has decent inherent balance so long as one started with matched bar size. Grip ain't much less than the typical single screw dog, either, and may be easer to avoid marring the work.
Rip big chips? Nooo.. not unless you want to put serious driving flats on the stock, first, then flip yer bars so their flat side, not the notch does the work.
"Not invented here". Learnt from one of the grown-ups, long time ago.
