1. Use KiCad to create circuit and layout.

2. Transfer the layout to the cut plotter software (e. g. Silhouette Studio if you own a Silhouette cut plotter).

3. Prepare the cut plotter with copper foil and cut the layout.

  • Cut off stripes of your copper foil tape with a length that is a bit greater than the desired width of the circuit. Cut as many stripes as you need to cover the total height of your circuit. Don't remove the protective foil.
  • Place the stripes on the cut plotter mat one below each other, giving you a copper plane large enough to cut your circuit on. When designing your circuit you should try to have as few tracks crossing from stripe to stripe as possible.
  • Cut your circuit.

4. Remove the unwanted parts from the cut layout and transfer it to the cardboard. The result is the final cardboard-circuit.

  • Cut off segments of transfer foil exactly the size of the copper foil stripes. Cut one per copper foil stripe.
  • Remove their protection foil and place them individually on each of the copper foil stripes.

Now for each copper foil stripe:

  • Pull off the transfer tape with the complete underlying copper part leaving the copper foils tape protective foil on the cut plotter mat.
  • Put the transfer tape on your workbench (transfer tape side down, adhesive copper side up) and fix it with some adhesive tape on the workbench.
  • Remove the unwanted copper parts with a pair of tweezers, leaving only the desired tracks on the transfer tape.
  • Take the transfer tape containing the copper tracks from your workbench and carefully place (adhesive copper side down) it at the correct position on your cardboard.
  • Use the backside of your fingernail to rub the copper tracks to the cardboard.
  • Peel of the transfer tape leaving the copper tracks on the cardboard.
5. Assemble and solder the cardboard-circuit.

6. Connect and test the build up cardboard-circuit.

The above procedure works for mid size experimental circuits. It requires some additional care when designing the layout but it avoids the complexity of making a printed circuit board.

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