Nothing special about tools : a budget press drill, that allows to drill "straight", in particular when you beginn the grip, when the block still has straight faces. It's easy to set the height of the plate, to drill at rhe right depth in the wood. You can even use it as a router/milling machine, when you make a grip in two parts.
Spade drills for wood : you remove material by drilling, and you finish with gouges and chisels.
Gouges and chisels : I had a few, but not very valuable, then I forged two HSS drill bits and a 12 mm wood spade drill, quenched them, ground and honed them to have more specific tools. I like working steel, it's rather funny !
A caliper, a ruler, a square, a kind of variable protactor.
And of course, a plenty of rasps, files, some "modern", some very ancient, from an old grand-father, a wood saw, and sanding paper.
But the most important is my previous grip, which is almost perfect for my hand, with a natural alignement of the front sight in the notch of the rear sight, even when I raise my arm with the eyes closed !