On Tue, 3 Sep 2019 18:29:20 -0700 (PDT), AK
wrote:

I am trying to find a bottle holder than can accommodate
a bottle that is 3.5 inches in diameter.
Not having any luck.

Think metric. 3.5 inches = 89 mm

The third URL seems to be the most productive:
https://www.google.com/search?q=large+bicycle+water+bottle+cage
https://www.google.com/search?q=oversized+bicycle+water+bottle+cage
https://www.google.com/search?q=89mm+bicycle+water+bottle+cage

Photo searches are also useful if you're looking for a particular
style:
https://www.google.com/search?q=89mm+bicycle+water+bottle+cage&tbm=isch

This list looks like a good start, but seems to be lacking in
dimensions:
https://bikepacking.com/index/oversized-bottle-cages-for-bike-touring/

Bingo:
https://www.cyclingabout.com/cargo-cages-anything-cages-oversized-bottle-cages/
The maximum capacity for almost all oversized cages is 1.5L
(52oz). There’s a standard diameter for bottles of this
capacity (89mm / 3.5 in) that allows them to fit soft
drink, Nalgene and many stainless steel bottles.

This might be of interest:
"Topeak Modula XL Bidon Cage Owner Review"
https://aushiker.com/topeak-modula-xl-bidon-cage-owner-review/


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558