OK, have now got a pic of my flower!
I had three different diameter cardboard tubes, so I cut them all up and fitted them inside each other - as I couldn't find my hole punch or sisal string at the time, I put tiny blobs of PVA on the 'petals' to stick them together - of course, the punch and string turned up about an hour later
so I tied it to the bars.
I put some Science Selective biccies in the petals - Smokey took them out very, very carefully and I don't think she's looked at it since! She's now dug a pit in her substrate right under the flower, so it's a bit of a stretch to reach it...but I like how it looks and she will suddenly decide to chew it to bits, I'm sure!
I have got more tubes now so I'm going to make one the same as yours too.