Search: " BMW aluminum gas tank " –
A number of craftsmen & shops out there who offer BMW specific tanks,
and even more who hammer alloy that may be willing to negotiate a deal.
Bring your big purse, though,
beating alloy is highly skilled work (for good product),
labor intensive, and not cheap !
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CRo's tank was built to my specs by
Evan Wilcox.
Here's one by Tottimori with a K-brick tank:
K-brick tanks are dirt cheap ! But will require some hands-on or $$$ to fit, etc, etc,