after going through many trays , I found something that works well, and ends you buying trays, its called coroplast its an oil base plastic when the arcylic dries it can be cleaned with any scraping tool, I use a palette knife. dry paint comes off like butter

where can you get this well any election sign or advertising sign use the back side, make sure that elections are over, you don't need problems, also many companies use these for promotions , what it looks like its white and ribbed in the middle of two layers. I picked up a few sheets after the company detour signs where no longer needed. cutting up these gave me 20 trays

its not the money, this saves me time cleaning and other related work