The other day I walked past another bike seat covered with a plastic bag, and I thought, "there has got to be a better way!" In some ways, the plastic bag is a great solution to a sopping wet bike seat - it's free, and it reuses an item that would otherwise be in a landfill. There are downsides, though - they tear easily, and the dangling plastic is constantly getting caught on things. I tried to maintain the spirit and advantages of the plastic bag bike seat cover by using...plastic bags. This project is still free, and still recycles. It adds strength and a clean look, and will keep your bike seat dry for a long time.

Step 1: Tools and Materials

Materials:
- Four plastic shopping bags
-Shoelace or string

Tools:
-Iron
-Soldering iron
-Parchment paper
-Scissors
-Marker

Step 2: Welding the Plastic Sheets

1. Using scissors to cut the handles and seams off of four bags.
2. Take one bag and fold it "hamburger style" so that it makes roughly a square. Sandwich it in between two layers of parchment paper and iron it. The time and temperature will vary, but it's better to start slow. The bag should burn or melt, just lightly fuse together. When you think you're done, roll the sheet between your fingers. If you feel it separate, iron a bit longer.
3. Take your second bag and fold it over the welded sheet so there is fresh plastic covering both sides. Place it between parchment paper and iron it until it is an even 4-ply sheet.
4. Repeat with the last two bags, this time folding "hot dog style."
5. When you're done, you should have two 4-ply sheets, one long and skinny and the other roughly square. Trim off the edges.

Step 3: Taking Shape

1. Take the square sheet and trace your seat onto it in the middle. Be generous with your line, it's better to have more material than not enough.
2. Cut out the shape, leaving an additional 1/4" outside of the line for a seam.
3. Iron the seat shape one more time to seal the edges.

Step 4: "Sewing" the Seams

Putting the two pieces together is a lot like sewing. Work inside out so that you can hide any unsightly work.

1. Line up the front of the seat shaped sheet with the center of the hot dog sheet. Using the soldering iron, tack the two edges together, once again working between sheets of parchment paper. This will be the starting point.
2. Work slowly in one direction, maybe 1/2" at a time, keeping the edge of the seat shape even with the edge of the hot dog sheet.
3. When you get to the back of the seat shape, return to the front and work in the other direction, until the seat shape is fully enclosed.
4. Using your fingers, close the sheets over the front of the bike seat and draw a rough line. You'll seal this seam between the front of the seat and the post.
5. Seal the hot dog sheet in the back of the seat, and trim off any excess.

Step 5: Finishing Touches

1. Fold the top of the hot dog sheet over about 1/2", and make a seam, leaving a tube for the drawstring.
2. Attach a shoelace to a safety pin and thread it through the tube.

Finished! If you have any questions, leave a comment and I'll get back to you!