Pretty readily available. Tyvek himber envelopes by Alan Wong. They make both vertical and horizontal versions.

https://www.penguinmagic.com/p/19736

https://www.vanishingincmagic.com/stage-......velopes/

https://alakazam.co.uk/products/tyvek-hi......ng-trick

This is Don Wand

Congratulations Simon on a remarkable effect you have truly put together a Real Worker. You have covered so much in your tutorial I can tell you have taken the time to make this one of the Best trick of the year so far. My Honest Opinion!

This is not a one trick pony Simon has given different ways to perform Tricolour. I believe this could be a EDC you would be Proud to own!

I am Impressed of what went into this project. It has Rhyme and Reason and has been Very Well Thought Out.
What's also nice is that you could perform this different ways for the next time you see the same people.

Simon has Truly Shared a Wonderful effect with the Magic Community.

Best Wishes
Don Wand

I agree this is such awesome product, it has to be a certain criteria for me to add to my sets, and this fits the bill perfectly for me, and very nice product and very nice routining with it too