Generate format following strings - random order

The Problem at hand

Currently, I am working towards making a code generator for reasons unnessesary to the question.

The Codes follow the format of 00|letter|8string mix|letter

Examples of expected end results are such:

00b06c1161bc 00aee797645b

00c435ab439e 00da494a229a

A quick breakdown of the middle 8 section string results in the requirement of a maximum of two alpha-characters and 6 numbers that can be in random order.

While Im having difficulty with this, there becomes the added problem of the limited letters accepted. These are the letters, a,b,c,d,e, and f

I've made a list (acceptedChars=["a","b","c","d","e","f"]) for the generator to pull from, however how to allow it to use this towards generation following the requirements I am unsure of how to pull off.

Any info on this would be wonderful, if you have any questions, comment and I will be sure to respond to it.