GRS Custom Guitars is a Brazilian luthier shop based in Campo Grande, Mato Grosso do Sul, founded and operated by Vander Pinesso. The workshop builds electric guitars and basses to customer specifications and also handles repairs, positioning itself as a small custom shop rather than a production brand.

The shop's output centers on bolt-on and set-neck takes on classic designs — Telecaster-, Stratocaster-, and Les Paul-style instruments — built with customer-selected woods such as mahogany, ash, and cherry, and outfitted with hardware from makers like Wilkinson and Gotoh. Through-body stringing is offered as a standard feature on their T-style builds, and pickup, finish, and neck specs are chosen per order.

GRS is known within the Brazilian guitar community for offering hand-built customization at prices well below imported custom-shop instruments, and the shop takes commissions and inquiries primarily through direct messaging on Instagram, Facebook, and WhatsApp.

GRS Custom Guitars has 1 product cataloged on Equipboard, including Solid Body Electric Guitars. Their gear is featured by 1 artist, with the strongest followings in Funk / Soul. Notable users include Mateus Asato.