Solar viewer is very easy to make.
1. 2' A4 Size Paper = Take a paper and make perfect circle on paper and cut the paper in perfect diameter.
2. Plastic Board = Here, again take a board and make little bit big circle and make a hole on it and then put paper on a board to adjust the diameter.
3. Box = Take medium size box.
4. Wooden Scale
Don't put small pin hole on a paper and duct tape because sun brightness and diameter appears small on board but Life is change use big hole for clear to understand your subject.