Jo asked how I did the Tyvek leaves without them distorting. The short answer is very carefully.
Here’s the long answer:
First, I stamped several extra leaves on the Tyvek so I could choose the best ones out of the bunch. After that it’s just all about keeping a careful eye on the Tyvek as it shrinks. Apply the iron (heat) to the back side of the Tyvek as it will want to shrink away from the heat, and I always use a piece of baking parchment as a ‘press cloth’ when dealing with Tyvek. Then place the iron over the Tyvek/parchment so that the iron is touching but not really weighing down on the Tyvek, trying to cover as much of the piece in one go as you can. Then just keep checking it to see if it has shrunk down to the texture/size you want it to be. The key is to check it every second or two so that the Tyvek doesn’t try to shrivel up and become crispy. Once the bulk of the Tyvek has shrunk you can go in an touch up other areas with the tip of the iron or a mini-iron.
Hopefully that makes sense to you, Jo! The secret is to just let it shrink slowly and not try to rush it. :)