Got a single-saddle-style moped and having trouble carrying passengers?
Here's how to make a tandem seat for a moped or motorcycle from any cushion that's roughly the right size and shape.

I got this armrest cushion from a boatyard dumpster.
I suspect the fabric is UV-resistant.

Step 1: Before

Ryan's moped has a seat that leans back too far, and no place for a passenger.
You can do it, but it's uncomfortable and probably dangerous.

Remove the seat. Ride around on the moped like that.
Believe it or not it's already greatly improved!

Step 2: Cut Off the Protruding Seat Support

Now there's a spiky thing where the seat used to be.
Cut it off So it's about level with the remaining luggage rack.
Smooth off the remaining jagged burrs.

Step 3: Wooden Seat Base

Cut a board just a little smaller than the wide face of your cushion.
This one is 8"x27".
It's 3/4" poplar pretending to be birch.

Round the corners.
Round the edges.
That will make it less likely to bite holes in the cushion or you.

I used a tablesaw, beltsander, and router table with 1/2" diameter qarter-round bit, but a handsaw, knife, and sandpaper would work just as well.

If you can't find the right kind of cushion, it's easy to modify one if you have a sewing machine,
or you can just upholster your board as seen in other instructables.

Step 4: Mark and Drill Boltholes

Mark the locations of holes to bolt the board to your moped.
Whittle a skinny pencil to reach through existing holes in the luggage rack and mark your board.
Drill holes for the bolts.
I used 1/4" -20 thread per inch carriage bolts.

Step 5: Add Bolts

The bit I had handy was a little undersized, so i used a hammer to put the carriage bolts in the board.
These bolts are good because the wide head has a square nub to keep the bolt from turning.
Perfect for carriages in fact.

Step 6: Put the Board Inside the Cushion

This cushion made life easy by having a zipper.
I unzipped it.
pulled the foam block out.
Put the board in with the protruding bolts facing down.
poked the protruding bolts through the fabric.
Stuffed the foam block back in
zipped the cushion back up.

Step 7: Bolt and Enjoy!

I poked the protruding bolts through the holes in the luggage rack, put washers and nuts on them, and tightened them up.

Then I took a ride on my cushy new seat.

Nice!