Design is one of my weakest areas so I really enjoy watching professionals put things together.
The rose arrangement is notable for the two tiers of roses. The tall bunch has the outer petals removed, most of the leaves and then is tied together.
These are placed onto a frog.
The lower roses are trimmed very short then placed on the outer edges of the frog.
The sunflower arrangement is interesting in the mechanics behind it. You have fabric held together in frames that allows light to shine through. The frame also has some magnets glued to the frame. The sunflowers are placed in small black plastic containers that have magnets on the back.
Thin wires are threaded through the stem behind the leaves. The wire is wrapped around the stem of the leaf. You can then bend the leaf to cover your container.