We have a counter height island that needed some chairs, so I decided to make them. They're composed primarily of 2x3 sections joined with pocket holes.

Step 1: Materials

Wood

6 2x3s (8')
2 1x6s (8')

Tools

miter saw
sander of your choice (belt or disc might be easiest)
pocket hole jig

Hardware

1 box 1.5" pocket hole screws
1 box 2" pocket hole screws

Optional

Kreg Plugs or dowels to plug holes
Wood glue

Step 2: Cuts

There's nothing fancy about the materials so everything could be cut to width in one go with the chop saw.

2x3x8 (6)
- 8 @ 12"
- 8 @ 14"
- 4 @ 25"
- 4 @ 40"

1x6x8 (2)
- 4 @ 12"
- 6 @ 17"
  - NOTE: The cut list image says 15.5". It's supposed to be 17".

Step 3: Drill Pocket Holes

The 12" 2x3s, 14" 2x3s, and 12" 1x6s got pocket holes drilled on one side and at both ends. The 2x3 sides with the pocket holes will be facing inside, so if there are any nicks or knots you can use that side of the board to make it less visible.

Step 4: Prep & Sand

I filled in some of the more obnoxious knots with a little wood filler. Then, since I wanted to stain the wood, I decided to do a full sanding regimen. I also softened all of the corners and edges quite a bit.

80 grit paper on a disc sander
120 grit paper on a disc sander
220 with a sanding block by hand

Step 5: Assemble Back & Front

I laid out 2 of the longer legs, and then lined up one of the seat backs at the top and the other two inches below it. I clamped the legs together snugly but loose enough to move around with a light mallet tap, and tried my best to get the backs flush with the face of the legs. After multiple attempts to make things square and even I was reasonably happy so i tightened the clamp slightly and glued and screwed them into place.

Next I put a clamp loosely on the bottom of the legs to hold the bottom two pieces. I positioned the seat support stretcher 15" from the top of the piece, and the bottom support stretcher 12" below that. After a bunch of tapping and measuring to make things as square as possible, I tightened up the clamp and screwed them in place. I didn't use glue on these for two reasons:

I read a few blog posts about pocket holes not needing glue. There's also some good videos showing that it doesn't add anything to the strength of the joint. It does however help keep things tight as screws may loosen over time... so time will tell if it was a good decision or not
It was a bit of a mess on the seat backs. I sanded a lot of it away, but it's not as clean as it could have been

For the fronts I just used the same measurements as the bottom half of the backs.

Step 6: Assemble Sides

Similar to the back and front pieces, I laid everything on its side, clamped it loosely, and tapped and measured until i was happy with how it lined up. It was challenging to get the top lined up perfectly, but it's not the end of the world. You can use shims before attaching the seat if things aren't perfectly level. Once I was happy enough, I screwed them in place.

Step 7: Kreg Plugs

After the backs were fully assembled, I glued Kreg Plugs into the seat back pocket holes. Since they will be the most visible part of the chair, I wanted to make them look a little nicer. The stretchers are far less visible, and I didn't glue them in place, so I left those holes open. I may also want access to them in case things got squeaky and needed to be tightened down the road.

As I was researching how to finish pocket holes I found this instructable from fixthisbuildthat that shows a variety of techniques. I thought it was pretty awesome and shows a few ways do this without having to but the premade plugs. I'll probably opt to use dowels in the future.

Step 8: Fit Seat

I wanted the seats to extend all the way to the back of the chair, so I needed to cut a notch off of the two side boards. I used a square to take the measurement, and then used a jigsaw to sneak up on the cut. I ended up making it a pretty tight fit. Tight enough that it wouldn't wiggle, and loose enough that it would go together without any friction.

Step 9: Sand and Shape Seat

After the seat was the fit I wanted, I decided to clean it up and blunt the edges.

I went across the front edges of all three boards, and down the side of the two side boards with a roundover bit on my router.
120 grit paper on a belt sander to clean up the large surfaces
220 grit paper on a palm sander to get rid of any major lines and to really clean up edges and corners

Step 10: Stain and Seal

I forgot to take pictures of my process, but it's similar to what I've done on other instructables.

I wet the wood very lightly with a damp rag to help raise the grain and left it to dry. After a few hours I used a rag to apply a liberal portion of stain to all sides of the chair (the seat isn't on it yet, but the rest was already assembled), and all sides of the seat boards. The chair dried standing upright, and I placed the seat boards on top of small pieces of scrap wood to help them dry uniformly and to limit the surface area that was touching something. Using the recommendation on the side of the can, I waited about 3 minutes before wiping the excess stain off.

After letting the wood cure for a full 3 days (it was a little humid) I applied 2 coats of polyurethane with a synthetic brush, waiting a little over 3 hours between coats. Because there was no way to prop up the seat boards without a wet surface touching the table, I did two coats on one side along with the edges, and then two coats on the other the following day.

After letting the urethane cure for a couple days, I sanded very lightly with 000 steel wool anywhere there were bumps. I did not apply a third coat.

Step 11: Attach Seat

I dry fitted the seat onto the char and flipped it upside-down on my workbench. Then I placed 12 metal angel brackets about where I wanted them (4 front, 4 back, 2 on each side). Because I assumed the seat would move a little as they get used, I only attached the brackets to the seat, not to the chair itself. This keeps the boards snug, but allows them to move up and down a little, or be removed if so desired. Because it was already such a tight fit, this worked out quite well.

After sitting on the chairs I noticed the wood on wood squeaked a little, so I also added some cheap weather stripping tape like you can use for windows between the seat and the frame.