My mom has seen a lot of my projects that incorporate LEDs into clothing and so for Christmas, she said she wanted light up slippers. She has peripheral neuropathy after undergoing chemo. It wakes her up at night and she wants to get up and walk around the house but doesn't want to wake up my dad by turning on the light, so these are the perfect solution.
I made these slippers from scratch, but you could definitely mod some slippers and skip most of the sewing.

Step 1: Materials

-8 LEDs
-2 coin cell batteries
-2 coin cell battery holders
-2 slide switches
-foam
-fleece, furry material anything you want to make the slippers out of.
-sugru to make treads(optional)

Step 2: Make Pattern and Cut Out Pieces

I used this instructable to make the pattern for the slippers. I am using the furry fabric for the inside and off-white polar fleece for the outside. Use a pair of slippers or flip flops to make your base pattern. Cut out the foam for the soles, then cut out the fur for the soles. It should be about .5 inches bigger than the foam. Cut out the fleece for the soles making sure they are about 1.5 inches bigger than the foam because they have to wrap around the foam.
For the top of the slippers, I used the technique they used in the this instructable. Cut out two tops from the fleece and two from the fur is at least two inches longer than the fleece. This will be folded over and your LEDs will be inserted.

Step 3: Put Together Circuit

The circuit is fairly simple, with just a few LEDs, possibly some resistors (I didn't need any), a battery and a switch. There are a lot of instructables about electronics so I won't go very in depth into it.
Solder together your circuit in a compact way using a soldering iron and make sure everything is well insulated so there is no chance of a short.

Step 4: Sew Together Slippers

Pin the pieces together the two top pieces together, folding over the fur and pin to make a tube to put your circuit in. Baste these together and repeat for the other side.
Place right sides of the soles together with the tops in between and sew from the middle of one side around the toe to the middle of the other side so the front part is sewn togehter with the heel open. You can turn the the slipper right side out. It should now look like a slipper, sort of!
Put the foam inside the sole.

Step 5: Final Touches

Slip your circuit inside the tube you made for it at the opening of the top. Sew up the heel of the slippers.
If you have wood or tile floors I would highly recommend making treads on the soles of the slippers with sugru.