I am working on a educational display to showcase Light Logic and how it works.

https://hackaday.io/project/166376-light-logic-diode-resistor-logic-out-of-its-cage

This is a combination of NAND, OR and AND gates to create a working XOR gate. And as the same for all Light Logic gates, transistors are not to be found. Just diodes and resistors. Power leads are under the paper to better show the logic wiring.