I live in the USA and am interested in building my own floats. Can anyone here direct me to a source that sells float components, stems, bodies, etc? Here I can only obtain poorly designed sytrofoam bodies. Thank you!!
Have you a Model Shop near you that sells remote planes, boats, etc? If so try it for Balsa Wood Dowel as this is ideal for making bodies up with.
Stems can be made with a variety of materials from the ultrafine bristles found in a Yard Brush to canes used for supporting young plants availble from a garden store.
It's just a matter of practicing with different materials. I once made some stick floats for river fishing using dried rosewood and balsa - they were so finely balanced that they worked perfectly 
I have experimented for many months with various materials including balsa. It's funny that you mention rose wood as just the other night I was out doing some yard work and noticed the "foam-like" material in rose wood. I would very much like to get my hands on some balsa or foam bodies as I am looking for consistency from one float to the next. It's strange that there are so many companies out there that sell floats but none that I can find that sell components. I will keep looking and thank you again!