Silicone sleeve sizing for stretching

I’m about to make some silicone sleeves for myself, and am hoping for some advice on internal sleeve diameter vs penis diameter for a secure but not super constrictive fit.

I am using the smooth on 00-30 silicone.

So say your penis had a flaccid diameter of 1 inch, what internal diameter would work well?

I would think just slightly smaller than your flaccid diameter, perhaps 10%?

If not difficult, you could make different sizes and test what works best.