It’s been a while since my last ambigram; inspiration has been hard to find lately.
This one went very smoothly- I wouldn’t be surprised if it has already been done.
My Case Study entry for ambigram.com’s ‘Ambigrams Revealed’ book.
After watching a TV show about the universe (and not understanding most of it), I learned that dark matter was made up of two theoretical parts: Weakly Interacting Massive Particles (or WIMPs) and Massive Compact Halo Objects (or MaCHOs). That served as inspiration for this large ambigram.
The biggest hurdle was turning ‘halo’ into ‘interacting’, but other than that it went surprisingly smoothly.