*Side note: I learned a while back that not everyone knows the dollar store sells fake floral. It might need some extra glue because the flowers like to fall off their stems, and you'll likely want to fill out your arrangement with some higher quality fake flowers, but for bulk fake floral, the price can't be beat.
I was lucky when working on The Suicide at Roosevelt University, that there was already a stock of flowers and greenery to pull from, but I still needed six wreaths to create my arrangements. The foam wreath forms at the craft store were small and expensive. But these basic wire boxwood wreath forms were cheap and just the right size.
I traced the wire form onto some 1.5" scraps of pink foam, and cut out the foam pieces with a jigsaw.
and here is a view of the same wiring from the back side.
Some of the wreath forms I left pink, and just started adding flowers. On others, like this one, I wrapped the wreath in colored tissue paper and tulle first. The Tissue paper and tulle was thin enough that the wire stems of the flowers could poke right through, and into the foam without much effort.
The floral arranging itself was mostly just about finding enough flowers in the right color family to fill the space.
And here are some of the finished wreaths (we ended up making four and pulling 2 from stock).