Welcome to this Instructable on how to make an electric foot warmer. Today, I will be instructing you on how to construct this warmer from reusable or common materials through using induction heating as the source of this warmth. With that being said, you can start your journey below by gathering the materials and getting ready to create your own!

Supplies

Foam Board/Posterboard/Wood (I used foam board with a wood backing for stability and softness)
Optional: Glass or Copper Sheet
Nichrome Wire
12V regulated power supply
12V power supply connector
Soldering Iron with Solder
Connecting Copper Wire
Cardboard
Box Cutter/Xact-o Knife
Duct Tape or Cloth
Hot Glue Gun and Hot Glue

Step 1: Tracing the Feet

Take a pair of sandals or slippers and trace out the feet shape on your posterboard/foam board/wood
Ensure that your feet will fit in the space and take a small knife and cut a bit into the trace for the cardboard slots later
If the posterboard is too large, cut it down to a size that will fit under your desk or for portable use, my cutout was fitted for under my desk, where I use it most frequently, which is around 18 inches and 20 inches

Step 2: Laying Out Nichrome Wire

Take your nichrome wire, leave an extra 4-5 inches and start laying them down into the traced shape in vertical lines. For this design, I had 8 vertical lines on either foot space
Start to use one piece of tape for every strand and go up as you do, with the first piece starting at bottom, and the last piece being near the top. By the end, the rape should be in a diagonal pattern
Once you have 8 lines, start to lay the wire horizontally and continue to make lines
However, when you are doing this, make sure you tape down the overlapping places so the metal wires do not explicitly touch each other (this can cause heating issues that will result in high concentrating of heat that will result in less heat distribution)
Once you finish one foot, do not cut the nichrome wire, just continue with the existing strand and do the same process that you did for the first foot, and then leave 4-5 inches after you finish the process and then cut the strand off.
In the end, you should have covered both feet, have two hanging strands that we will solder, and have a connecting piece between the two feet

Step 3: Adding the Cardboard Edges

Cut out 6 feet of cardboard that is 1 inch in depth
I cut the 6 feet into 6 pieces of 1 foot each and applies 3 feet worth of cardboard for either feet
Start outlining the edges of the feet with hot glue and add each of the pieces on by one, shaping it with your fingers and holding it in place until it dries - insert each piece into the small cutout you made earlier so it helps it remain in shape
By the end, you should have an outline like the one pictured above, with places to put your feet

Step 4: Soldering the Power Supply Connector

Take a 12V power supply port and find the two metal ends on the port that you can establish an electrical connection to.
We are induction heating so we need a complete circuit where the electricity can travel through the wire and return to heat it
Solder one wire from each of the feet to either one of the ends on the power supply port and then you should have established your connection.
You can glue the port to the posterboard/foam board/wood that you have

Step 5: Finishing Touches

Some optional changes or additional you can make include adding duct tape layers on top of the wire so you can feel the heat without having to feel your feet jostling the metal or concentrated heat regions or adding cloth on top if you want a more plush and blanket-like feeling for your feet as it heats.

Additionally, I added a small wooden sheet below the foam board that I used so that it does not collapse under the pressure of my feet or fold and that it is able to remain a solid structure. I used a thin layer of wood to do this as well in order to maintain its portability and its ease of carrying as it is not too heavy.

With these changes, your induction heated foot heater is now complete! You can take this wherever you go and use it however you like, just make sure to have your power supply with you and plugged in to supply the heat and within a few seconds you should feel it heating up and supplying you with the warmth that we all cherish in the fall and winter months.