Since a walker is designed to support much (if not nearly all) of the weight of an elderly human, the table is surprisingly strong and stable. I was able to stand my Clydesdale-like frame upon it during testing, though I don't recommend this as a substitute for a ladder. The design uses ordinary components from hardware stores and can be built for very little cost. If I were to make a Mk. II version, I'd find some way of attaching the work top to the walker once the walker is folded. Since this is such a basic design, it leaves a lot of room for customizing (larger or smaller work surface, small vice, tool storage, etc.) but this is my first go at an Instructable and I hope I did well! Comments and criticisms welcome.
Step 1: Materials
* A walker, preferably four legs with rubber caps (no wheels or skid pads) and currently not in use by someone (Aunt Edna and Uncle Sal will thank you)
* Four (4) split ring clamping hangers for 3/4 inch pipe (measure the diameter of the tubing near the walker's hand grips to make sure this is the right size; if yours is larger/smaller, purchase the correct size hanger for your tubing)
* Four (4) socket head cap screws , 3/8-16 thread, 1 inch long OR four (4) standard hex head bolts, 3/8-16 thread, 1 inch long
* Utility knife
* Screwdrivers, Phillips and flat head
* Plywood, 3/4 inch thick, 2' by 2' square or similar (used counter top section, butcher block, reinforced sheet metal, etc.)
* Drill or drill press with various metal and wood bits (Forstner bits if you want to make the bolts flush mounted)
* Hex key, 5/16 or sized to fit the bolt head (alternatively, you will be using a socket set for hex head bolts)
Step 2: Release Your Grips
2. While it cuts easily, it has been formed tight to the metal through manufacturing and multitudes of hands bearing down on them. Slip a screwdriver under the cut and pry off.
Step 3: Time to Get Clampy
3. Using two of the clamping hangers, mount them loosely on one side of the walker. You will have to completely remove the screw from the clamp, put the clamp around the tubing, then close it back up using the screw. By leaving them loosely you can lay the plywood on top of them with the bolt thread section pointing up.
4. Slide the clamps along the tubing until you find that sweet spot that keeps level contact with the board while providing the widest distance between the two clamps. This will provide the most stable configuration for the work top. If you want to ply your dark arts of math and numbers on this section, do so. Have fun!
5. Oh, you're back! Have a nice time in Numberopolis? Once you've got the ideal spots located for the clamps, crank down on the clamp screws and secure them tightly to the frame. Repeat with the other two clamps on the same side.
Step 4: Topping It Off
7. If you are channeling the great flannel shirted marvel known to mortals as Norm Abrams, remove all screws and break into your Forstner bit set. Forster bits will drill a clean flat bottom in wood, allowing you to flush mount items like bolts and cap screws with ease. One thing I didn't think through (or photograph) was that, by flush mounting the cap screws, I did not take into account the height of the bolt would change the depth of the screws overall. You can go with one of two easy fixes: get shorter cap screws or (what I did) torque down on the screws once you encounter some resistance when it hits the bottom of the threads and starts to hit the frame. Back the screws out completely and remove the clamping hangers. If you've done it right, you'll have a slight circular score mark where the end of the screw "bit" into the metal. Drill out the walker frame with an appropriately sized bit, reattach the hangers, top and cap screws. The drilled openings will now give you plenty of room to fit the screw down flush to the surface and helps to anchor the top since you're now incorporating the frame into the equation and not just "floating" above it.
That's pretty much it. I've already used it a few times in my shed for supporting boards to cut, holding tools off the ground and generally enjoying my creation while mentally listing ways to improve upon it. Hope yours turns out just as awesome!