Creating a complex UID thats not a GUID/UUID in the normal sense

Creating a complex UID thats not a GUID/UUID in the normal sense

I am looking for suggestions to create a incremented ID (much like a
license plate number). Instead of the usual 0-9 int32 type counter I am
looking for something can go 0-9 then A-Z for each character in the
sequence.

So I would have the potential to have a 6 char ID that would be '2A3DC3'
This has the potential to give a much greater depth to the available
values.