Me too wondering how to do this. If you sand flush after attaching to the blade, you will muck up the knife.
Pete
I covered the blade and guard with masking tape. Used the blade tang to outline the right and left scales on a piece of 1/4" rosewood. Cut the outline, with some margin, on the scroll saw. The guard is curved and about 3/16 at the thickest, so I clamped one scale to the tang, pressed up against the guard, then marked the shape of the guard on the edge of each scale with a pencil. Used a 220 grid belt on the sander, a little at a time, to taper the scale on that edge to that mark and kept fitting it against the guard. When the scale was a good fit and just flush with the guard on each side, I clamped one scale on and drilled through the 3/16 hole in the tang into the scale for the brass thong tube. Then remove that scale and clamp on the other scale to drill it. Then epoxy on both scales and tang, press the thong tube through, and clamp all until the epoxy set. Then go back to the spindle and belt sander and sand the handle and epoxy overflow down to flush with the tang (the fit to the guard was already good). Then clamp the blade in a vise (wrapped in a shop rag) and hand sand to get the scales smooth. Some sanding hits the edges of the tang but it is a hardened stainless steel (Rc 54-56) so not much scratching. I am waiting for some rouge to go back and polish the edges of the tang, but they already look pretty good. The blade and guard were protected by the masking tape and did not get damaged.
It's a little bit of work, but nothing too tough. The tang on this knife had 8 holes for pins to pass through the scales, but I figured the epoxy plus the thong tube was enough, and I like the look of just clean hardwood on the handle. I use the thong hole to attach a tag with the knife features and the price. I set the price to $50 for the rosewood and $55 for the same knife (#2) with Longan Berry scales ripped from a pen blank (the pen blank cost $5; I had the small piece of rosewood left over from another project). I'll negotiate if those prices are too high.
I thought for the 3rd knife for this show I might try a piece of Purpleheart for the scales - just for something different. I'm not ready to try the home-made Micarta yet, but maybe next show. How about canvas layers, then cutting up a $1 bill for the outer layer of the Micarta? Might attract some attention.