JML Guitars (also operating as JML Instruments) is a custom guitar shop based in Indianapolis, Indiana, run by luthier Jay Lewis. Lewis builds handmade, one-of-a-kind electric guitars and basses to customer specifications, with a particular emphasis on neck-through construction. He came to lutherie through years of playing in underground punk and metal bands, and a stated goal of the shop is to keep custom instruments accessible in price rather than positioning them as boutique luxury items.

The shop operates on a made-to-order basis with extensive customization options, alongside occasional non-commissioned one-off builds. Models have included the Singlecut-style electric and a design called the Mushtronaut, with graphics created in collaboration with artist Steven Yoyada. JML has also done collaborative builds with Dunable Guitars. In addition to commissioned instruments, the shop sells available builds through Reverb and merchandise through Etsy.

JML Instruments has 2 products cataloged on Equipboard, including Solid Body Electric Guitars and Electric Basses. Their gear is featured by 2 artists, with the strongest followings in Rock and Metal. Notable users include Thomas Jäger and Mika Häkki (Monolord).