I made this bench a while ago and have been meaning to write an Instructable about it. Sorry if the pictures don't make much sense, i didn't take any while making it.

Step 1: What You Will Need

1 2x4 @ 8' long

3 1x4 @ 8' long

1 2' x 4' sheet of 1/2" plywood

3-4 hinges

Screws

2 large bolts at least 5" long

- 4 nuts and 6 washers to fit the larger bolt

2 smaller bolts at least 4" long

1 sliding bolt lock

The most expensive things here were the bolts, i went for the cheapest i could find at Home Depot. The total for all of the items above came to around $25

Step 2: Cutting the Wood

I left the plywood top of the bench at 2' x 4' because at the time i only had a jigsaw to use.

I then cut one of the 1x4's to a length of 4'. This was used to attach the bench to the wall.

Another one of the 1x4's will be cut again at 4' leaving two 4 sections for the front and back rails beneath the bench

The last 1x4 will be cut into 4 lengths of 22" (assuming the 1x4's are actually 1" wide). These will fit inbetween the rails adding support.

I figured out roughly what height i wanted the bench which i think was around 36"

I cut the 2x4 into 2 36" pieces and from the remaining i cut 2 6" pieces.

Step 3: The Bench Top

I first started by attaching the two 4' side rails to the top. I just screwed through the top down into the rails. I countersunk the holes so they wouldn't stick above the surface.

I then attached the 22" cross supports making sure everything was square. Again i just screwed through the side rails into the 22"pieces. I then screwed through the bench top into these cross supports to give some added strength.

Step 4: The Legs

For the legs i needed a way to fold them up and to be strong enough to support a decent amount of weight. I also needed a way to lock them in place when they were down so it would be safe.

I came up with this method of using he large nuts and bolt as the pivot, and the smaller bolt as the locking pin.

I attached the 6" 2x4 to the inside of the side rails on either side of the bench that would be away from the wall.
I then clamped the 36" 2x4 to these 6" pieces so it was flush with the front rail and with the underside of the top.
I then drilled the holes for the large bolt and the small bolt. There was no real measuring with these holes i just put them in the middle of the 2x4 and in the middle of the side rail for the large hole.
I then removed the leg, and rounded over the end with a jigsaw as you can see in the picture, allowing it to rotate freely.
I could the legs on. I put a washer on the outside, in between the pieces of wood and on the inside of leg. I used two nuts to keep it in place. (you could use a nylock nut but they were more expensive)

Step 5: Attach the Bench to the Wall

I mounted the last 4' 1x4 to the wall using screws. Making sure that it was level and the top was at a height of 36"

I then mounted the hinges to the top of the front face like you can see in the pictures.

Then using some clamps and bungee cords i positioned the bench on top of this piece. It should sit right on there in the upright position. Make sure that the hinges are located at the top of the 1x4 side pieces and not on the plywood or it wont sit level.

Step 6: Securing the Bench to the Wall

I used a cheap sliding bolt lock to secure the bench in the upright position. I drilled a hole in the side of the bench top where the lock lined up. Be careful of the size lock you get though. With the plywood only being 1/2" there was not a lot of room for the hole without splitting out the wood.

Step 7: Finished Bench

I was really pleased with how this turned out, to say i just kind of winged it. It was really cheap too, at only $25. You could probably use some pallet wood for the underside of the bench top and that would save some money. It strong too! It took my 250lb standing on it to do some work in the rafters without any fuss.

Thanks

Phil