Dimpled left HS skin with c-frame dimpler on interior holes and pneumatic dimpler along the edges. Worked great, except holding the skin open enough to hit the ram squarley was sometimes hard. I used a pop rivet dimple tool on the front three holes for center nose rib, and the vice grip dimple tool on the front holes for the tip rib. Neither form a dimple exactly the same as the c-frame / pneumatic dimpler dies, but they will work well enough. I'm really glad I bought these various tools already. There might be other ways to get the job done, but the proper tools give better results easier as usual.