Step 1: Materials and Tools
Rare earth magnets. I had a bunch of different sizes lying around from a 50 piece sampler pack from Lee Valley Tools. Cost: about $0.35 per magnet.
Sugru. This stuff is a handy formable silicone sold in small packets. Cost: about $1.50 per packet.
For the magnetic task lights, you'll need some LED keychain flashlights. Cost: about $0.40 per flashlight.
For the magnetic reacher, you'll need a stick of an appropriate length and a large flathead screw. I used the dried stem of a small walking stick cabbage, but I seriously doubt many people have these lying around in their airing cupboards! A dowel would be just fine.
For the magnetic apron closure, you'll need an apron (or some other piece of clothing you want held closed without having to tie a bow).
None of these hacks cost more than $1, because I only used 1 pack of sugru for all of them. In fact, I had half a packet left after making the closure, two task lights and the reacher, so I mended the plastic stand for my hot glue gun that I'd broken. Total build/mend time for everything: less than the sugru handling time of 30 minutes.
Step 2: Task Lights
Stick a small disk magnet to the LED flashlight, and mold a thin layer of sugru around it. Take care to avoid the screwheads so you can change the batteries if need be. If you have a particular tool in mind and a location, you can custom mold the sugru to it by first covering the surface with cling film and pressing it into the appropriate spot. Leave to cure overnight. That really is all there is to it. The pictures show two variations on the theme: one for general purpose - the video shows it placed on a power drill:
Step 3: Magnetic Reacher
The reacher can pick up quite heavy things (see pictures - a 1.25 kg weight was no problem). I wandered around my basement renovation picking up nails and other stuff, and got dozens before needing to empty it.
Step 4: Magnetic Apron Closure
Cut the apron tie close to the side. Open a packet of sugru, and cover a magnet with a thin layer. Press into the tie, then fold over the end. Repeat on the short side. The stronger you want the magnetic closure to be, the thinner you should make the sugru (and vice-versa, of course).
Step 5: More?
Here's one my son came up with - a task light at the end of a stick - by combining a task light and the reacher. He thinks it would be useful to see what's under the table. Or as a big magic wand. He doesn't want a pro membership, though!