A band of independent builders who take the field together. You keep your autonomy and trade the lonely parts of going solo for the strength of a company behind your name.
Engineer A brings in Client A — it's a big job, so engineer B, designer C, and PM D join. First year, each billing $25k for the month.
Note that B, C, and D pay the same 25% they'd pay on any work handed to them — referred work carries no penalty, so there's every reason to pull teammates in rather than turn overflow away. That is the whole point of a company.