I imagine a hard money lender will use my current properties as collateral?

You could secure the lien with another real property or personal asset with a substitution of collateral agreement in place. 

He suggests I buy lot outright and use this as collateral for demo and construction loan. 

Now he just needs to cash a check each month when the payment is due - no need to wait for the mail man.Write in an early payment discount in the event you sell the building and pay off the seller financingUse a stutter clauses - allows you to miss one payment a year.Build in a substitution of collateral clause - that means you can move the security of the mortgage to another property with equal or greater equity when you sell without having to pay off the existing mortgage - therefore not having to pay off the mortgage gives you more cash at settlement.DON'T ask for seller financing - it is SO easy for the seller to say NO Way - BUT write it in to the offer - it will be much easier for the seller to understand.If the seller resist seller financing - build in a short term balloon 6 - 12 monthsLet the seller know he can make more money (in interest) if he helps you will financingGive the seller some great references (financial and testimonials) sellers like to deal with people they trust and like.

A new company called Salt Lending is giving out short term loans with your crypto as collateral (just bitcoin and ethereum atm) up to and over 1 million.    

I also invest in PPR's note fund, it's probably a little safer since it a fund, many assets are your collateral, vs. hard money where your money usually goes into just one deal. 

If they remain commingled, you're really just collateralizing the investment in a way that likely won't be advantageous to you as property owner of things don't scale with the PM company.

The IRA could lend to others with similar returns, collateral, and terms.  

This is a business loan to the LLC, and not collateralized.  

I like your idea of using a property as collateral for a private loan especially if I can't find a bank loan after trying several.