This instructable shows how to make a side bag/purse out of old bike tubes and billboards/vinyl.

*I very much suggest to read my how to sew bike tubes/vinyl instructable before you make this!

What you'll need to make a Side Bag/Purse:
-Old bike tubes (26" or 29" are the widest. just ask for these at most any bike shop).
-Vinyl (I use old billboards. I called up Next Media and they gave me a few free ones).
-Lube (I used cooking oil because it's cheap, biodegradable, wipes off easy, and leaves a shiny coat).
-Most any sewing machine with a leather/denim needle and adjustable tension.
-Polyester thread
-Hot glue gun for tacking tube in place before sewing (optional, but makes it way easier/quicker. you can use clamps/safety pins too.)
-A clasp: i use a bike cog in this instructable. You could also use valcro, buckles, buttons, snaps, nothing - whatever.
-A strap: I use an old one ripped off another bag. Or you can make one out of seat belt, more tubes, etc.

For more things you can make out of bike tubes/vinyl check out my other instructables:
The Wallet - Male
The Wallet - Female

Step 1: The Body

Tube
1) Cut 4 tube lengths of about 2'x4" (I usually cut a couple standard 26" tubes into 3rds to equal about this dimension. If you're a little off, oh well. see my "sewing bike tubes basics" instructable for how to do this.)
2) Sew together into a sheet (pictured). Don't worry about the tube lengths being a bit uneven.
3) Use a ruler (an 90 degree L shaped works quick) to draw straight lines at either end of the tubes - cut.

Vinyl
1) Lay tube sheet down on vinyl.
2) Trace tube sheet to back of vinyl using chalk or paint marker. Allow either end to be a half inch shorter than the tube sheet.

Step 2: Inside Pocket

Inside Pocket
1) Cut a tube or two a little longer than your vinyl is wide (the extra length is to account for uneven cuts and tube stretching/compressing)
2) If your desired pocket depth is wider then one tube, use two tubes and sew together. Cut more narrow from there if you'd like.
3) Lay tube(s) across width of vinyl. mark and cut straight to match.
4) Lay tube(s) on vinyl. Trace to be 1/4-1/2" shorter than the tube(s) on the long side.
5) Tack (hot glue is best) so vinyl is flush to bike tube on 3 sides. Let the 4th side be 1/4-1/2" shorter.
6) Fold bike length of bike tube over length of vinyl. tack. lube. sew.
7) Lay pocket 1/2-2" below top of vinyl and flush with sides. tack. lube. sew.
8) Mark straight lines vertically along pocket sheet for where you want individual pocket divides. Lube. Sew to vinyl.

Step 3: The Body: Fuse and Clasp

The Body: Fuse and Clasp

Body: Fuse
1) Lay vinyl face up in center of bike tube sheet face down. This should mean it is flush on the long sides with about a half inch of bike tube hanging off either of the shorter length sides.
2) Tack the long sides together. Fold the excess tube ends over onto the vinyl and tack. Lube and sew just the shorter ends for now.

Body: Clasp
*Note: There are all sorts of ways to clasp the flap of your bag to itself. Valcro, buckles, ties, buttons, snaps... list goes on. I got a little weird and used a bike cog. So I'm gona tell you how to use a bike cog.

Clasp: Cog
1) Cut about a 4" piece of bike tube. This is your time to use those narrow tubes if you got them. Otherwise, a thick one could work.
2) Stick your piece of bike tube through the cog. Fold over the tube so it sticks off to one side of the cog.
3) Lay the folded together piece of tube down on the outside center of the bag just below the pocket (or further) with the cog facing up toward/over where the pocket is. (Make sure it's below the pocket, or you're going to sew your pocket shut!)
4) Tack, lube, and sew "X" pattern for strength.

*Note: so, if you couldn't tell yet, I'm not big on measuring to the inch but rather to what materials you have. To figure the best place for sprocket placement - fold the bag into 3rds (as if it were really the shape of a bag) with a few inches extra inches on the flap to account for where the base will be. Place the sprocket just below where the flap folds over.

Clasp: Cog Tie Loop
1) Cut about a 2" piece of thin bike tube. Otherwise, a thick one could work.
2) Align to the middle top of the flap long ways flush to where the tube folds over the vinyl.
3) Tack. Lube. And sew top and bottom of tube piece.

Clasp: Cog Tie
1) Cut a 3-4' x 1/2" strip of bike tube.
2) Run through tie tube clasp. Center. Tie into a small wrist size diameter loop.

*Note: The tube strip does NOT run THROUGH the cog, but rather raps AROUND the cog so as the teeth hold it in place and it can easily be slipped on and off.

Step 4: The Sides

The Sides

Body Sides
1) Fold front of bag body to desired length of front wall. I usually do it just under my pocket at about 6-7"
2) Cut two wide tubes to match this length.
3) Lay tubes on vinyl, trace to be about 1/4-1/2" shorter than the tube.
4) Tack vinyl to be flush with 3 sides of the tube, leaving about 1/4-1/2" of tube excess on the top.
5) Fold tube excess over vinyl. Tack. Lube. Sew.

Strap Loops
*Note: you can use thick bike tube, skinny bike tube, straps, or whatever for the loops you will be attaching the strap to. I used old bag strap because they're strongest.
1) Fold strap piece in half. Align to side body so it's center and the top of the loop is flush with the top of the side body.
2) Tack. Lube. Sew in "X" pattern for strength.

Step 5: Sew Body Together

Sew Body Together
1) Take sides and measure them from the top of the pocket side of the bag body. Mark where the side ends with tube side of body up.
2) Line sides up to mark of body. Lay sides vinyl side up facing toward each other the long way.
3) Tack, lube, and sew the bottom of the sides to the sides of the body.
4) Fold sides to meet sides of body. Tack, lube, and sew inside out.
5) Once all 4 walls are sewn to the body, turn inside out!

Step 6: The Strap and Finish

The Strap

So, I just swiped a strap off one of those old trashy purses/side bags you find at the thrift store. You know the ones made of cheap vinyl with some conference or college logo on it that they give away and no one ever uses. They have decent straps with clips. The thrift store I went to gave me a few trash bags of these things for free just to get rid of them. Reuse is reuse!

If you want to make your own strap out of a seat belt, see my Bike Tube Messenger Bag instructable (COMING SOON).

Finish

1) Use a rag to wipe up lube. Use some extra lube to wipe entire surface to make shine.
2) Cut any sticking up threads.
3) You're done! Good job!