Financial separation in WA state

What is the name of your state? Washington

My wife and I would like to obtain a financial separation. We will remain married.
The situation is completely amicable and there are no financial issues in dispute -- everything split 50/50.

My question is this: Does a lawyer or mediator even need to be involved in this? Or is it simply a question of us filing paperwork without having to hire anybody?

Thanks in advance for your input!