I use bottles of hand sanitizer as hall passes in my 5th grade classroom. When students need to use the restroom, they place the bottle on their desk while they are gone and then get a squirt of sanitizer when they return.
The bottles are supposed to be placed back on the front table afterwards, but often are not and the next student who needs to use the restroom has to hunt for it.
I put these hall passes inside a plastic sleeve and use packing tape to attach them to my front table. Students are more likely to return the bottles when they have a clearly defined "parking space."