I love the TCRT5000 Reflective Optical Sensor. It's cheap and very easy to use in my arduino projects.
I created a mount to fixate the infrared LED and the infrared detector and to isolate and guide the pins to solder points where I connect the wires. The two snap in ears of the housing are still available.
PLA
0.20 mm
15% infill
The author hasn't provided the model origin yet.