Step 1: Stuff You Need
The plastic parts where taken from the plastic of the printer, be sure to find some straight sheets a cut them from there.
Step 2: Electronics
I didn't make a custom PCB, I reused the PCB from a previous ible and completed it with a protoboard, I will upload the files for the custom PCB when I finish it.
Step 3: Base
Once out I removed the cartridges and cut the platform in order to make it flat, here is where the board will rest.
Finally add two pieces of plastic in the borders for stabilization.
Step 4: Board
Step 5: Buttons Dispencer
Step 6: Sensor
While in the "scan mode" if the Ir transistor stops receiving the light it mean that under the sensor there is a black cardboard and that position is recorded.
The Ir receptor comes from an old dead mouse and the led Ir from a remote control.
The green led is there just for confirmation that it is working but is not necessary to use it.
Step 7: Finish
Let me know if you find any grammar mistake or need more information in any step.