I’ve designed and built a house to sell, I bought and flipped a foreclosure, and currently in a live in flip.

., and built into the cost.

I only recommend this route if furnishing the STR is not the long item.  

Best exercise is going on a job site and working with a contractor line item on pricing.  

The EPA has published new lead paint standards. https://www.healthday.com/health-news/environmental-health/e...All five of my rentals were built well before the end of the lead paint era.

You can do some sourcing yourself through Facebook groups, and online RE communities , and even pick up the phone and cold call some homeowners that may be tired landlords, don't owe anything, and have built up some equity.With enough volume, you should come across some solid deals.  

Look up top STR markets in US, look up "how to grow my real estate portfolio", look up "best markets in US for the BRRRR", start calling agents in markets, contractors, lenders, start feeling out who is a right fit for your team.I've built networks in two different markets and I can tell you ppl come and go and some start well and then slack, there's lots of trial and error because ppl are good on the phone.So you see there's so much going into this goal of yours. 

Albeit, when we building materials started to increase significantly, that complicated things and we had to just keep going.You will lose MORE if you sell a half-built property, than if you take it to completion. 

Then you have to think about 401(k) and IRA savings, which longer-term once your balance is built up, you can use a self-directed approach whereby you can use the funds tax-free to invest in rentals, private loans, etc... 

You can focus on properties that have strong rental potential to generate steady cash flow, helping you pay down the mortgages over time.Once you’ve established a solid cash flow and built equity, you can scale by adding more properties gradually.