Advice much appreciated about contract

[Tom Linnik]

Me and my partner recently came to an agreement with an investor we have been working for for some time. We came to an agreement we would work in a parntership with him flipping houses. The way we did it was where the investor would pay for the house and all expenses and material. Me and my partner would do all the work and when the house sell we would split the end profit 3 ways equally. I was wondering what type of contract we should write up or if a lawyer should be used. We have a good trust with him but would like to have it in writing just in case. We are already working on our first flip so any contracts or advice people have would be greatly appreciated! Thank you.