A step stool is a simple project and it is an excellent choice for trying dowel joinery. What I can do is goof it up and make it as complicated as possible.
I wanted to use dowel joinery for this project so i picked the up a cheap 3/8 inch kit from Harbor Freight.
I measured 12 inches for the seat top and used a block clamped to the rip fence so the piece does not get trapped between the blade and the rip fence and kick back into my face.
I take a piece of two inch wide board that I have on hand and cut it 10 inches long for a stretcher.
For the sides I measure in one inch from each side and draw diagonals from that mark to the corner on the bottom. The I come in two inches from the bottom on each side and find the center point 3 inches up, draw diagonals to make the shape of my side.
I copy the mark to the opposite side so I can make the cut without changing the miter gauge. I repeat this for both sides.
I use the band saw to cut the inner pieces out of the sides.
The first cut goes really well. The second?
I clamped down one of the sides and marked the center. I put the dowel centers in the holes that I drilled. I lined it up carefully and tapped it down to make marks.
I repeat for the other side.
Then I dry fit the sides together with some dowels
I mark the top so i can line the bottom assembly on it.
I pick the spots I want the holes in the sides and stretchers.
I set my depth back to an inch again and drill the holes.
Then I put dowel centers in the four outside holes because I only have four centers in the kit.
I line up the bottom assembly and tap to make marks.
I started to dry fit so I can put a dowel center in the middle hole and mark that.
And my favorite part of the project as always is sanding and sanding and sanding.
I use a quarter inch round over bit to round all the relevant sides.
Now I add glue to the holes and the sides and on the pins.
Make sure there is glue on the pin and insert the stretcher.
And add glue and pins to the other side and put it together.
Do something I didn't do and mark the top and the sides very carefully so when you put the top on you know exactly which way it should go, Then small variations on where your holes aren't a problem. If you go to the trouble of marking the centers and then forget to label it, you'll have trouble like I did where you have to keep trying it and then finally convince it in a little bit.
I finished it with some bright red paint.
Free plans are available in Sketch Up and PDF format.