A Shelf With 1 Screw

A simple shelf for a workshop
Material

You need a long board for the back and short boards for the shelf
Mark the position for the short boards where ever you want
Make Your First Cut

The height of the saw blade is 1/4 of the width of the long board
Add a Spacer

and make your second cut.
The width of the spacer = the thickness of your short boards minus the thickness of your table saw blade
Remove Material

make so many cuts you need
Adjust the Tablesaw

The height of the blade should be the thickness of the long board
Make a First Cut in the Shelf

You can calculate, where this cut is to make but it is not important. Somewhere near the centre is good.
Make a Second Cut

Use a 2nd spacer
The width of this spacer = the width between two opposite cuts of the long board minus the thickness of your table saw blade
Remove the Material Between the Cuts

Repeat this steps for any shelf.
Put the Shelfs on the Long Board

use a mallet if necessary
Drill a Hole

or 2, if you want.
Screw It on the Wall

and fill it with stuff.
Look at This Video

for all steps