I just rebuilt a long bow form last year that I use 1.5” glass and lams in. I stayed with the 1.75” LVL. And just took a router and mortised out slots ever 6-8” 1/8” deep on each side where I use my zip ties to center up bow in the form.
The extra mass in these LVL forms help with twist and straightness longevity.
Wheres the best place to get LVL. I couldn't find any around me. Granted I didn't look that hard.
The big box stores may carry LVL materials, but i've always gone to an actual lumber yard that supplies larger quantities to home builders and contractors to get mine. i want mine fresh from the mill that havent been setting in a pile and being handled a lot for a long period of time. how this stuff is stacked makes a difference how straight it is. just a thought... Kirk