How to Connect a Convex Face To a Concave Edge That Fits its Shape Perfectly I could not think of a different title that would make sense, so I apologize for any confusion. I'm modeling a fishing rod and am currently working on the reel handle. The face the handle will be extruded from is A, but it's staying as a just a single face this entire question. The long oval shaped piece that connects the handle, A, to the rest of the rod is C. This is the piece that allows the full motion of reeling, having a pivot point on both ends of it. My problem is that I need A to fit into B, which is the concave edge on on the inside of one side of C. When done, I can then fully extrude A out into a handle. Currently, I can't seem to find a solid solution of taking A and its convex circular shape and snapping it inside B and its concave shape. The vertices match up on one side of A and the convex edge of B, and I can fill in the gap left in C after A is inserted no problem, but its that inserting of A inside of B I can't figure out. I know I can Alt + M on the points that connect inside B no problem, but only half the points of A will be connected in properly. with the other half not flush and perfectly shaped and on the same plane, and leaving A not a perfect circular flat plane. I apologize that this is a confusing question, I can't figure out another way to explain it. I'll answer any questions I can to help explain it if needed.
You can get it there using Vertex Snapping


Enable vertex snapping
Set it to Active (this will snap the active vertex)
Select the circle and snap it to place


(You end up with some double vertices that need to be merged.)