There are 2 bar envelope variants by Frances Levangia that I want to focus on. The easiest and best [ https://ghh.com/elf/bar-envelope/ ] allows full use of the interior. This is the envelope I want to teach. The more ubiquitous version [ https://www.origami-fun.com/origami-bar-envelope.html ] is harder to fold and doesn't allow full use of the interior. I taught that version at PCOC 2017; and would like to briefly show it as time allows, for comparative purposes.
This envelope is the most practical envelope I've found. It's elegantly simple, and makes good use of the paper. It's also very giftable (and re-giftable by recipients); being a unique and hard-to-find homemade origami equivalent to a red envelope [ https://en.wikipedia.org/wiki/Red_envelope ] for giving checks, money, gift cards, etc..
I will show ways to improve these envelopes to give them greater structural integrity. The insights gained from the bar envelope can be mapped to other forms of origami, like pixel units. It's also a great way to explore ratios and scaling issues (especially for origami based on rectangles).
- The hardest part of this model is a locking fold that some students misfold as a squash fold. Also the last step is easier to demonstrate than to diagram. Basically it's a pretty simple model; especially once it has been learned.
OrigamiUSA will supply paper, to be handed out by the teacher in class. A calculator that can handle rational numbers and repeating decimals is optional but recommended for working with ratios.
Some links were provided in the description. Others can be found on Gilad's origami site: https://books.giladorigami.com/origami-database/Bar+envelope+Frances%2BL... . There are many other sites that feature videos and diagrams of the most ubiquitous variant of the bar envelope; many of which have no attribution.