There have been lots of threads about tax disc holders in the past - I even put some possible designs online. Its hard to come up with something that everyone likes... but thats life.
If you can summarise what it is you want, then I will gladly take this forward.
Personally, I think a circular cling design, or a shield shape would work best. Aluminium holders are too expensive to be stocked items.
On a side note, I do not wish for anyone to produce, sell or distribute any merchandise relating to Saxperience, without my prior approval. Things run smoother and are future-proofed when distributed directly via Saxperience.
Please also bare in mind, that if you can chew this over and sumamrise your view, thats more likely to catch my attention, than asking me to wade through 50 pages of comments