Counter-intuitively, this is not a stool with arms. It's a stool with feet that are arms. Were arms. Arms that are feet.

Mine looks like the picture. It is discarded desk chair arms screwed to a chunk of wood, and it makes a great footstool or hassock-that's-not-a-hassock. I made it because I was trying to find a use for the extra desk chair arms I had kicking around. I hate arms on desk chairs. They get in the way of my arms, which I think are more useful to me than the chair's.

BONUS: If you have fancy arms (chair arms) your stool is also height-adjustable! If you have fancy arms (human) it will make building this project easier. Neither kind of fancy arms are required, however, normal arms will work just fine.

Also, vote in the furniture contest! There is, unfortunately, no contest category for Grammatical Confusion so Furniture was the next best option under which to enter.

Step 1: Collect Your Stuff

To build this you need

Chair Arms, harvested from desk chairs you legally own or rescued from more dubious fate. I happened to have a few extras kicking around because I hate arms on desk chairs. They get in the way of my arms, which I think are more useful to me.

A top/seat of your choice, from similar sources. You need something flat and accomodating to screws, or glue something to it that will accomodate screws.

Other supplies I Used And You Probably Will Too:

Some Screws (I think I used 1-1/4" drywall)
#10 Washers
Wood glue
Screwdriver or drill
Clamps
Saw
Workbench
Time

Step 2: Make the Top Thing

Make your top/seat and/or get it ready to mate with your harvested arms. I made one out of scrap crate lumber from work and the math to cut an octagon took me longer than everything else combined.

To make a quick easy strong seat from scraps:
1. Collect your scraps of 1x lumber (I had 1x8), preferably all as long as the seat is wide.
2. Lay out two layers going opposite directions (like plywood, but thicker)
2a. If your lumber is crappy or you care about perfection, you should square up the edges on a jointer or table saw or something.
3. Put glue on top of the bottom layer
4. Put the top layer on the glue on the bottom layer
5. Clamp. I used an assortment of clamps (surprise) and a pile of 11/4" sheetrock screws. If you are smart, you will have planned for this side to be the bottom when you are done.
6. Wait for glue to dry, remove all the clamps and screws, and cut to shape as desired.

Alternately,
1. Use plywood or a log.

Step 3: Layout

Mock it up for form and function. Rework as necessary. For the record, an octagon with three legs looks silly and left me with an extra arm. As much as I would like it to function as a prosthesis, it is far more useful, aesthetic, and space-efficient on the stool.

Step 4: Put It Together

And confirm that it really does work. If it falls apart, fix it. #10 washers make sheetrock screws work well in 1/4" bolt holes.

Step 5: Finish It

Apply a finish of your choice, if you wish, like paint or varnish or stucco.

In the interest of time and lazyness I opted for the eco-friendly Natural Oxide Wood Patina. This requires only exposure to air and darkens gradually with time, but provides very little resistance to stains and marks of any kind. If you use this method then you are effectively finished.

Enjoy the joy of using your new handmade furniture from reclaimed stuff! It has proven equally useful for sitting on, putting feet on, and for holding up other things at random.