Update: The fit on the shaft is just slightly loose. I figure this is better than too tight, because you can always shim the shaft with a bit of tape or a dot of silicone to make the knob fit snug. Since there's bound to be some very small variation in the shafts on different machines, I'll think about a way to make a friction fit work a little better and maybe post a newer version with some changes, but for now this works pretty well. Designed to fit what appears to be a 1/4" (.250") D-shaped shaft. My washing machine happens to be a "Magic Chef" brand, but this knob should fit pretty much anything with a recessed shaft of these dimensions. The washing machine uses the same knob for the load size ('water saver') settings and for the hot/warm/cold water temp settings. It was missing one of the knobs, so luckily I was able to model up a perfect copy of the remaining one in SolidWorks. Replacement knobs for appliances can be purchased for between $15 and $30, which seems ridiculous. Printing the knob used about 10 grams of material, for a cost of about 50 cents for premium PLA and about 35 cents for standard filament. I took all the dimensions from the old knob with dial calipers, but I have not yet tested the fit. I will update once I've confirmed it fits the shaft properly. The shaft dimensions on the printed knob match the original to within .005", so I think it's going to be fine. Print this at high quality, 3 shells, 15% infill, 230* in PLA on a Replicator 2 with raft and supports turned on. The resulting object looks awesome. Print the tiny peg in high quality in a contrasting color and press it into the little hole in the knob, tapered end first. Should be a friction fit. Carefully shave the peg flush with the surface of the knob with an X-acto knife or something similar. If you wanted to use a set screw to firmly secure the knob to the shaft, I suppose you could just print it with enough shells to make the shaft area solid, and then you could drill and tap a hole for the set screw perpendicular to the flat face inside the shaft hole. If anyone wants a version with a set screw hole already in it, leave it in the comments and I'll try to add that feature.