I get that this is way out of the realm of home improvement, but I've always had great advice and help here and thought I'd give this a try. I'm going to work on a small project for my gym, and have looked at different standalone boxing equipment. What I'm wanting to do is take a 2x4 in a bucket and attach long springs perpendicular to it at different levels for punching. I'll cover the springs with a plastic sleeve and the sleeves with pieces of pool noodle. I want the springs so that the "arms" will come back to the same position. I'm trying to figure out a way to attach the springs to the face of a 2x4 so that they are completely secure and won't loosen and come flying off. I'll attach a picture to hopefully explain my idea better. Thanks in advance for the odd question.