I made a whole bunch that were extremely simple but very satisfying to the recipient. All from dowel stock. Dimensions to suit. Here is what I used.
Head: 5/8", ca. 3" long
Teeth and shaft: 3/8", shaft length - whatever feels right
Handle: 1". ca. 3" long
Drill 4 equally-spaced holes in a line in the 5/8" head for the teeth. Glue in 3/8" dowels to protrude ca. 3/4" (or more if you want longer teeth.)
Drill another hole centered between tooth 2 and 3 in the head at about 45° to the tooth axis for the 3/8" shaft. Glue.
Drill the end of the handle to take the other end of the shaft. Glue.
Drill a last hole in the handle, if desired, for a leather hanging strap (shoelace?)
After it is all together, hold the contraption vertically at the desired angle and saw the teeth at an angle on the table saw. The sharp part is on the same side as the shaft. I try to get the blade as close to the head as I can to keep the teeth short, but that's just me.
It is important to cut the teeth carefully with a fine blade to avoid splintering. By the way, the sharper the angle of the teeth, the better it feels, so don't go crazy with the sanding. It can always be toned down if the user finds it too aggressive.
Finish however you wish. I messed around with different stains for the different parts, but that is fussy. Salad bowl oil makes a nice finish, but it is just as useful with no finish at all.