I painted a vehicle for a customer, in the middle of the build he passed, he left no will so now I'm not sure what to do.
If you are holding the vehicle, you have a possessory lien under Texas Property Code Chapter 70. You are entitled to keep holding the vehicle until you receive payment.
You should consider writing a letter by certified mail to the vehicle's owner to demand payment. Attach your invoice and/or contract, and a photo of your work.
Good luck.