I use Tite Bond 3 exclusively for wood repairs, I find superglue works poorly on wood and becomes brittle and weak after a few years. When I need to add filler pieces, I find that cutting the filler piece into an irregular shape, with a very tight fit and solid clamping works best. If you use straight cuts, the joint is much more visible, especially in walnut. it is also important to spend a lot of time matching your grain pattern. I have tried tinting it with various dyes but it always looks VERY dark afterwards. I just finished a restoration/conservation on a funky old double barreled shotgun that had lots of breakouts around the lock panels and used undyed Titebond 3 and the joint lines are invisible. If you have some scrap pieces you could try to see what works best with some dye added. They do make Tite bond with a dark color, specifically for darker wood, that does seem to work better than tinting the regular kind but I still prefer the tightest possible joint method. Good luck, hope that helps. (If I wasn't so incompetent with my phone/camera and computer interface, I would show you . Sorry.)
