I've been plagued for years with a 1 car garage that did not allow space for a workbench. I finally decided I've had enough and needed to come up with a workbench that would fold away to allow parking of my wife's car, as well as be sturdier than the 2 plastic sawhorses + piece of plywood I've been using.

Supplies:
5 - 2x4’s
22+ – 3” Wood Screws
18 – 2” Wood screws
3 or 4 – Old door hinges
18 – 1” Wood Screws
2 – 3/8”x3 ¾” Bolts
2 – 3/8” Nylon lock nut (Nyloc nut)
6 – 3/8” Washers
1 – 3/8” – Drill bit
1 – 4’x8’x¾” Sheet of Plywood
2’ – Web strapping (or rope to be used for handle)

Tools:
Saw
Drill
Measuring tape
Level

Step 1: Dimensions

Determine desired Length and Height of workbench. For the legs of the bench to fold up inside of the table top, your length will need to be at least twice the height plus some.
The Depth of your workbench will need to be less than your Height. (In my case I had to deal with the Footing extending up past the floor so my Depth was 4” less than my Height) If you get your Height just right, your workbench will rest on the floor when it is folded down.
My dimensions: 79” long, 36” high, 32” deep

Step 2: Build

Use three 2x4’s and some deck screws to build the workbench frame using the dimensions you came up with in Step 1. I put 1 cross member in the very middle of the frame.

Trim another 2x4 to be at least 4” shorter than the length of workbench (let’s call it the Swingframe). Center the Swingframe onto the underside of the workbench frame. Secure it to the frame using the Old door hinges and 1” screws. Mount the hinges so the hinge pin is facing out from the 2x4’s. This allows the weight of the workbench to be fully on the Swingframe.

(I saved the leg building for last, to account for the uneven/slantyness of the garage floor.)

Step 3: Step 3 Mount

Mark your workbench height on the wall and draw a line using the Level as a guide.

Using the deck screws mount the Swingframe and workbench frame to the wall. I used 2 screws in every stud it covered. (It helps to have a friend or two hold the frame in place at this point, because you haven’t made legs yet)

Once you have it mounted on the wall give it a few test swings to be sure you clear the floor.

Step 4: Legs + Tabletop

Hold the workbench in the open/up position and measure the distance to the floor in the two front corners.

Cut the remaining 2x4 to these lengths (they may differ depending on the slant of the floor).
Holding the legs, in place drill a 3/8”hole through the frame and leg.

Trim the top corners off of the legs to allow them to swing freely.
I also made a cutout on the outside of the leg to allow them to overextend and rest against the sides of the frames. I didn’t want a leg to fold up on me while working on the bench.

Insert bolt in this order, bolt-washer-frame-washer-leg-washer-nut. (Not sure if the washer between the frame and leg are necessary but seemed like a good idea). I got carried away and countersunk the bolt into the frame. Not necessary but I didn’t want it to snag on my clothes.

Step 5: Top and Handle

I tied the web strapping around the front of the frame to use as a handle.

Cut the sheet of plywood to the size of your workbench frame and mount using 2” wood screws.

Enjoy your new fold-downable workbench, it's sturdiness and space-savingness will be the talk of the town.