Perch shaped jerkbait

what are the spikes on the back of it?

These spikes are just for esthetic purpose and they made outusing the sea fishing line.

how do you atatch them? small holes drilled and epoxied in?

The bench vice was used to keep firmly jerkbait in the desired position meaning at the angle. And like you said, the holes were drilled approx 2cm into the body and epoxied in. For the spikes, sea fishing line 1 mm in diameter was used.