I should have taken a few pics of the process but I use a small spring clamp to hold the buffalo horn to the tang and mark one pin location using the 3/32 drill bit in the pres. Remove the horn from the tang and drill it through then rub the back of the horn on 100 grit sandpaper to remove the chip out on the back of the hole. Return it to the tang with a hold pin. (my hold pins are simply steel nails sanded down till they are a smooth slip fit in the pin hole) With one pin in place I can make sure the horn is correctly aligned and mark the second hole. The drill and sand routine is repeated.
Now with 2 hold pins in place I can mark and drill the third hole and when the back side has been cleaned off I can return it to the tang and scribe the top and bottom lines which gives me a "square" to place the slice of 2 inch pipe on to mark the front and rear curves. When the four lines (profile and curve) are cut on the bandsaw I can then do the clamp, mark and drill to the second piece of horn using the first as a template and with its lines bandsawn the two can be hold pinned together to sand and polish the front of the bolster curve, while the rear inside curve is left as it comes off the 60 grit paper on the drill press mandrel. They are now a mirror image of each other and in the case of having and order for a pair of knives(as is the case this time) with this treatment I can use one bolster as a template for the curves placement for the second knife