What are some common investment devices for rental properties?

My understanding is that if you issue a promissory note longer than about 7-8 months it's considered a security, something I don't want. However issuing a promissory note at 10% for 7-8 months sounds like a lot of money to pay in that amount of time.

These would be friends and family lenders so I know that that has some sectionsb in the securities laws but my understanding of securities laws isn't quite up to speed so please fill in the gaps where necessary thanks.

I'm not sure where you get the 7-8 months thing. If you issue a promissory note for a lien on a property, you indeed are an issuer of a security. However, you aren't breaking the "security laws"(*) because your F&F lenders are performing 'Exempt Transactions' in the eyes of the security statutes.

As an excercise, look up the law in your state and find the section of code that exempts security interest in real property. In NC, it's 78A-17(5).

(*) Assuming, 'normal' F&F lender deed-of-trust, where indebtedness secured by a lien or security interest in real (or personal) property and the entire security interest together with all the bonds or other evidences of indebtedness secured thereby, is offered as a unit.

Not legal advice. This post is for entertainment purposes and as always, consult a licensed professional in your state when dealing with preparing recorded documents.