If you happen to own a iRova K6L robotic vacuum cleaner, you can trick the robot there is a virtual wall using black electrical tape. The idea is to use a black electrical tape to trick the cliff sensors built in the robot and it will move away from the black tape line. Effectively you can use it to create a cheap virtual wall to draw a border for your robot vacuum. However, I have tested this method on the iRova KK8 and it did not work unfortunately.
This is how you can make a home made negative film scanner by using a shoebox and your digital camera. The basic idea here is to use your digital camera (campact, DSLR or even smarphone) to capture the negative to a digital image and use a photo editor to invert the negative image to color image. Before you go and pick up your digital camera and start snapping your old negative films, you will need a light box to illuminate your negative films, and a jig to properly hold your camera in place to avoid shaking when you snap the negative image.