I assume that you meant that the urethane won’t release without mold release or grease. I consider urethane to be an adhesive so I wouldn’t try it without mold release or maybe a thin coating of Vaseline applied with a cotton swab.
I’ve cut the bottom plates down to 1/8" and added a bevel at the bottom of the 18 holes in the mold. I’ll begin the printing in the morning after I return from my aquatic PT (stroke). At high resolution, to keep it smooth, printing will take some time. I think I’ll try Platinum silicone first, then urethane. Wish me luck, I’ll post results.