Here are instructions for a simple leather purse. No sewing is required, just some leather cutting (which is easiest if you have access to a laser cutter) and some lacing.

The purse is about 9" x 9" x 3" when finished.

Materials required (all are available at Tandy Leather)
1) leather (I used a large scrap of vegetable tanned leather): $20
2) lacing (I bought a 35 yard roll of lacing, but only about 3 yards were needed for the purse): $35
3) a lacing needle ($5-$10)
4) a razor (for cutting lacing)
5) a laser cutter (if you don't want to cut the leather by hand)

Attached are five files with the specific pattern I used:
1) a .dwg file (autocad file) at full scale (inches)
2) a .dxf file at full scale (inches
3) a 1/4 scale pdf with a few dimensions
4) a 1/4 scale pdf with no dimensions

5) a full scale pdf with no dimensions

I made it at Techshop: http://www.techshop.ws

Step 1: Cut Out Your Pattern

You have a few options:
1) Be a warrior and use a razor or scissors to cut your lines a drill (1/8") or leather punch to make your holes
2) Get with the times and use a laser cutter

Step 2: Thread Your Needle

There are a variety of needles to use with leather lacing. The type I used was a "Perma Lok" 1/8" lacing needle from Tandy Leather. For this type of needle, you:
1) cut the lacing at a taper
2) put the sharp end of the lacing in the hole
3) twist until it feels solid

Step 3: Bend Your Tabs

If you used vegetable tanned leather, as I did, then you can mold your leather using water.

1) take your center piece (the long rectangle with the tabs)
2) wet the tabs with a damp sponge
3) bend the tabs at a 90 degree angle

This will make lacing the center piece onto the faces easier.

Step 4: Start Lacing the Front Piece to the Center Piece

You may have noticed that there are two more holes in the front piece than there are in the center piece. The first and last holes in the front piece do not have corresponding holes in the center piece.

1) start your lace by going through the first hole in the FRONT PIECE ONLY
- needle goes in on the rough side of the leather, comes out on the smooth side of the leather
2) leave about six inches of lacing hanging on the rough side of the leather
3) go through the SECOND HOLE in the FRONT PIECE and the FIRST HOLE in the CENTER PIECE

You are now set to start lacing all the way around.

PS: Don't worry, we'll finish off that hanging end later.

Step 5: Finish Lacing the Front Piece to the Center Piece

1) continue lacing (up through one hole, down through the next)
2) keep your lacing straight. if it gets twisted, just un-twist it before you pull it tight
3) when you reach the end, thread through the last hole in the front piece (with no matching hole in the center piece)
4) leave yourself at least six inches of slack

The slits you cut for the tabs will allow the center piece to conform nicely to the curve of the front piece.

Step 6: Tie Up the Loose Ends

prep) thread a needle onto your six inches plus of extra lace and wet down the top edge of the front piece with a sponge (so it will stay when you fold it)

1) thread the lacing through the first stitch (needle pointing inward)
2) pull tight and crease the top edge of the center piece (which you just got wet)
3) start threading back and forth underneath the other laces
4) make sure to pull the laces tight under the edge of the leather so they are least visible
5) after three or four passes, cut the lacing close
6) you have now tied up the loose end without an unsightly knot

REPEAT this process on the other side of the front piece (tie up both loose ends)

Step 7: Lace on the Flap Slot

Now, before the back is sewed on and in the way, is a good time to lace on the small "flap slot" that will hold the flap to close the purse.

1) thread down the top left hole
2) up the bottom left hole
3) down the bottom right hole
4) up the top right hole
5) thread both loose ends through the bottom loop and pull tight
6) leave 2-3 inches hanging as a decoration

Step 8: Halfway Done

You should now have the front piece laced to the the middle piece and a "flap slot" laced to the front piece.

Step 9: Lace the Back Piece to the Center Piece

The procedure is exactly the same as it was for lacing the front piece to the center piece, with two exceptions:

1) this time the front piece is in the way, so it's a little more cumbersome
2) you don't fold and crease the edge of the back piece when you tie up the loose ends

NOTE: You don't have to have the extra holes in the front and back pieces. If you don't want a folded top, just skip the first and last holes when you make your pattern.

Step 10: Add a Strap

The simplest way to add a strap is to buy a pre-cut leather belt from the same place you got your leather. You can also cut your own, but you'll need a big piece of leather (expensive) to get a long strap.

1) cut the ends of the belt the way you want them (a simple triangle looks nice)
2) cut four holes to match the four holes on each side of your center piece (using your method of choice: I used a 1/8" drill bit)
3) lace the strap on using the same technique you used for the "flap-slot" on the front

Step 11: Admire

Credit for the original design goes to this image that I found when searching for purse patterns. I copied the proportions pretty directly, but had to make up the dimensions to get everything to the size I wanted it.

OPTIONAL EXTRA: since this was a gift for my wife for our third anniversary, I also used the laser cutter to burn the text of my wedding vows on the inside of the flap.