The DeVere 5108 handwheel is an aluminum casting. The O.D. (Outside Diameter) is 5 inches (about 127 mm). It is 1 and 5/16 inches (33.27 mm) long from the front of the wheel to the back of the hub.
The two shafts: focus and head height, are 0.500-inch diameter. So, the clearance hole in the handwheel must be slightly smaller to fit, say, 0.502 inch or so.
The hub diameter is 1.0-inch diameter (25.4 mm).
The hub is fastened to the shaft by a spring roll pin of
approximately 1/8-inch diameter. It might be slightly smaller. The length of the roll pin is 1 inch. They are driven or pressed into the common hole between two parts to fasten them together. The hole is smaller in diameter than the pin. Due to the slit in the pin, it springs to compress to fit the hole tightly. Before installing, the pins are somewhat larger in diameter than their nominal size.
Here is a table of standard inch-based spring roll pins. It lists the required hole diameter as well.
https://www.almabolt.com/pages/catalog/pins/springroll.htm
As noted in post #4, there are many prefabricated handwheels available.
It will be cheaper to buy a prefabricated wheel than to have one made. Any handwheel designed the fit a 1/2" (0.500”) diameter shaft should work. Outside diameters or 4” or 5” are most suitable. Note that some of them are fixed to the shaft with one or more setscrews. Such a setscrew-fastened wheel will work on the DeVere.