This card can be used to estimate distances of common things. human size, car, semi, suv, door, and Connex shipping containers. 

after printing tie a string through the hole with two knots at 50 cm, hold the end of the string in your mouth or at your chin and look at the card compared to the object being measured.

this is the original drawings and information FOSS-R CARD Beta see this for any questions.

ive included the step and fusion360 files so you can modify it as you want.

leave a like if you find this useful!