Kind of depends on what you mean by sophisticated. X-Ray imaging has gotten surprisingly affordable: https://www.ebay.com.au/itm/386247465197 https://www.ebay.

Kind of depends on what you mean by sophisticated. X-Ray imaging has gotten surprisingly affordable: https://www.ebay.com.au/itm/386247465197 https://www.ebay.com.au/itm/386247465197 (honestly I was looking for canister X-Ray machines which are a bit safer for this, now I'm seeing these things and thinking "is my search for a way to find joists in walls actually over?)