[These plans were developed before my discovery of the Kreg Jig, these plans don't require the purchase of any specialty equipment]
One can easily construct a work bench for $25 with the following:
7/16" OSB (4'x8')
2 1/2" Coarse Thread Drywall Screws
Wood Glue (Optional)
Note: How much wood do you need? See the next step to design your own.
Countersinking drill bit
Miter saw (Optional)
Nail gun (Optional)
Step 1: Size
1: My regular workbench. This is a tall, sturdy workbench that I use on the regular. Although I just have my miter saw below, its great for stacking boxes or storage totes. I've used this bench as a step stool to work on the ceiling and it felt very stable the whole time.
2: Light-weight cart. It's only light-weight because of the cheap wheels. I use this piece to do some light moving and also set recently painted or stained items on it so I can wheel them outside to dry. The design is some-what reversed than the other two. This is not finished on the bottom; I didn't put the bottom shelf because this thing is always moving. Note: The width and depth are 20", but because of the design the cart is actually a rectangle. Think about this when designing your own bench if you have specific needs.
3. Our finished product. The bottom shelf is dropped to the bottom of the legs (unlike the bench in #1) because it will have wheels. The bottom shelf is short because I used a scrap piece of wood that was just that length (I'm trying to make good use of my wood).