It's not just with guns that things are banned in stupid ways. Take whip-its:
Hey, do you want to get high like your parents did in the 70's? Find a convenience store and pick up a pack of whipped cream chargers, more popularly known as Whip-Its! You've likely seen these contraptions around at the occasional gas station and wondered why a box of devices used to make whipped cream cans work have any place among the racks of Cheetos and Snickers and such. Simple, those little cartridges are filled with nitrous oxide. You might recognize that as the "laughing gas" you're sometimes given during particularly gnarly dental procedures. Doing it in large quantities will get you high as shit, and that's why possessing it in large quantities is something only dentists and a few other select professionals are allowed to do.
To get around that, it's sold in tiny quantities as a culinary tool, with most users opting to buy the party-in-a-bottle by the box or case. There are sites online that will sell you 240 whipped cream cartridges for less than $100. You can't freely buy a giant tank of nitrous oxide, but you can totally buy enough nitrous to fill one without much hassle. As this story will attest, you can do so at your neighborhood convenience store or market even.
But banning a boxes with springs will definitely work. The whole cracked article is a little microcosm of criminal ingenuity.