A rangefinder is a piece of equipment that will help you to measure the distance of stationary objects such as buildings. It is possible to make your own simple rangefinder with a few household materials. Though this type of rangefinder will still help you measure some distances, it is not going to be as accurate as a digital rangefinder. This can double as a science project if you are a student.
Scrape half of the silver off a surface coated mirror with a knife or sharp object.
Draw two 1.25 inch diameter circles onto the piece of cardboard. Use a compass to draw the circles.
Cut the circles out of the cardboard using a knife or a pair of scissors.
Draw a circle slightly larger than the diameter of a thumbtack at the centre of one of the circles.
Draw a rectangle that matches the length and thickness of one of your mirrors at the centre of the same cardboard disc.
Cut out the rectangle and the circle shape with a knife.
Place the wooden beam on a flat surface with the 3 inch side pointing upwards.
Place one of the disks on one of the edges of the wooden beam and insert a thumb tack through the centre of the disc to estimate where the discs will go on your wooden beam.
Glue the two cardboard discs together using multipurpose glue.
Mount the two discs onto the end of the wooden beam where you had estimated previously and drive the thumb tack through the discs to hold them onto the wooden beam.
Glue the unscratched surface coated mirror onto the centre of the two discs using multipurpose glue.
Glue the scraped mirror with the scraped side down and at a 45 degree angle on the edge of the wood opposite the cardboard discs.