My white satin sheets are just big enough to fit your required outer layer size. Can you supply a vector drawing?
I usually cut a 2nd inner layer (spacer) if the 3mm isn't thick enough, but I could pick up a 5mm acrylic sheet since I'll be at my supplier later this week..
Contact me at mail < a plus t> machinecollective <d+0+t> org, so we can discuss further details, I'll make a nice price for your custom order.