If you have a local metal supply shop, you can ask them. They'll normally cut, or sell you remnants.

You may need to do some cleaning and polishing.

This is 0.070, about twice your thickness.

https://www.ebay.com/itm/Grade-9-Tit...S/123147916963

This appears to be sold by the inch (in 6" increments).
https://www.titaniumjoe.com/index.cf...55:0.035:SMLSS

With a variety of sizes and thicknesses.
https://www.titaniumjoe.com/index.cfm/products/tubing/