Sales invoice creation

I organize workshops for multiple participants. Sometimes I have fifty or hundred participants in one session. Is there a way to send out invoices without having to create a new customer.

That depends on whether you want to manage the amounts owed by each participant separately.

If yes, then you need to setup each participant as a customer.

If no, then setup one customer to represent all the participants and create invoices for each participant and charge it to this customer.