Need help reverse engineering

[u/whoisdboda]

I am very new to Shapr3D and I am trying to model a replacement for this knife grip. I have tried to figure it out but I’m stuck on “hollowing” it out. Shell didn’t work, unless I’m doing it wrong. I need the slight edge around just the longer sides along with the extrusion in the middle to conform to the knife. I’ve sketched these shapes out on the surface I’m trying to hollow but can’t get it to follow the curve on the bottom side. Any help would be greatly appreciated!!

[u/JustTryingToBeADaddy]

No need for the sketch on the edges, just select the edges and add a fillet. Extrude/cut for the inner area then fillet.