Divide everyone into smaller groups of three or four composers each.
Each group should spend fifteen minutes preparing for an improvisation lasting no more than eight minutes and no less than four minutes. Each goup's improvisation will be tape recorded.
Between you, divide your improvisation up into reasonably equal sections, bearing in mind that faster, more active music generally requires more work.
Discuss the general shape of the taped material and decide whether any general areas could be improved upon, for instance, by returning to a previous texture more than once, or by not returning to a previous texture at all, (or by never getting to it in the first place).
Decide on a set of instruments that you feel appropriate for the piece: use conventional instruments if you wish. Keep the instrumentation within the composition group unless you can garantee that another instrumentalist is available.
Re-compose the piece in fully-notated form according to the divisions you agreed upon earlier. Keep checks with each other, especially over areas such as the joins between sections.