I went about this all backwards! First, I decided I wanted to make some art for a small opening in a bigger mat. Then I got the mats made. THEN I sketched these. Oh well, I never claimed to be a rule-follower!
I saw one of these in the Montreal Botanical Gardens years ago, and wanted one ever since. This has been here for 2 years now, and it is growing nicely – I just have to keep trimming off any shoots that want to grow straight!