****y123......
Many float makers on FM as a quick search will show!
For example, Lord Paul of Sheffield ran a thread (Float making) back in June last year which may go some way to answering some of your questions as many amateur float makers contributed, including myself. On the same page as this thread, another titled 'Binka's Bobbers' also appeared, and this covered Binka's attempt to start making his own floats and this again may well answer some of your questions.
Over the many years I have been involved with FM, float making in all its forms, including materials, design, paints , varnishes etc. have been discussed in depth, so a comprehensive search would offer lots of help..............The advice freely offered by some folk has been invaluable to me!
Anyway, ask your specific questions, and those of us who enjoy the labour of love which is float making will be unable to resist the opportunity of offering lots of advice!!
ps I make at least a dozen every month, many of which are to suit given situations on the waters I fish and with the materials I have to hand or easily available, but that doesn't mean I don't buy some that are outside my own DIY skills.....
Okay, next question........................................