I have used Cerakote on my personal items, guns-both metal and plastics, anvils, clevis pins and hooks, etc.
As long as the surface is clean and is etched, scratched or some way to provide pours for Cerakote to grab onto I would not expect anything less that great service from the product.
Use the "Plastics" formula for oven temp, gas out and cure if using their "H" product.
One lesson I learned the hard way.
Don't cure metal at the 300 degree temp and then...to do the plastic, don't just open the oven door and turn oven down to 150 and wait for "oven heating" light to come on and stick your plastic in and time for 2 hours.
The oven will hold a heck of a lot of heat and heat everything to a crisp.
Do the reverse if you have picked a day to tackle all.For plastic or JB Weld - Low oven temp first , then pull and heat up to 300 for metal parts.
I know this sounds so obvious and I of all people should know better being the son of a 35 year Sherwin Williams man.
I'm not a professional painter but I know a bit about prep and chemical coatings...but I did it.
Hope this helps!
Michael