Hoping this will be of some use for some people wanting something different to the traditional flowers.
Firstly, you will need to collect alot of buttons in your colour scheme. Ebay, junk shops, chairty shops, carboots, fabric shops etc will be your best friend! I am also using lace and pearls/beads for mine, aswell as various brooches. I have found that taking apart a cheap flower garland from Asda leaves white fabric flower shapes which work quite well at the bottom of some of the button flowers.
The button flower stems are florist wire, it comes in a range of colours including white, I don't intend on having mine showing when the bouquet is finished. It comes in different sizes. I used 12 inch/20 swg wire. It's easily manipulated and not too thick to fit buttons and beads onto. It's fairly inexpensive, again, Ebay is your best bet.
You need to decide how you want the flowers to look, so do a few mock ups before putting any on the wire. Once you've decided, bend over a couple of inches of the wire at one end, and thread the top button on first, then the second and so on. I find a maximum of 3-4 buttons to each stem is fine, but it's up to you.
Once you have thread all your buttons for the flower onto the wire, twist the remaining wire as tightly under the bottom button as possible to secure it and repeat with the rest of the button flowers. You can add lace to the bottom of these too, I use a hot glue gun to attach the lace underneath the bottom button once thread onto the wire.
Some finished button flowers -
There are probably a number of ways of turning your button flowers into a bouquet but I have decided to use La duette oasis bouquet holders. (Dry ones, not wet).
(This pic is just a mock up which I threaded onto my pomander base)
Any gaps will be filled with lace and beads threaded onto craft wire. I'll use organza ribbon or nice vintage lace to cover the underneath part of the oasis and secure the florists wire to form a 'handle', which will be tightly covered in matching ribbon. I have no pics of a finished one as mine isn't at that stage yet - I still need LOTS more buttons to complete it.
Here are examples of how it should/could turn out -
Hope this helps some DIY Brides-to-be!