Oslo Instrumentfabrikk is a small custom guitar workshop founded in 2012 by luthier Thomas Hagen Kaldhol in Oslo, Norway. The one-person operation builds electric guitars, basses, and lap steel guitars, and also handles repair and restoration work. Each instrument is built to order and numbered sequentially.

The shop's designs draw on classic American offset and semi-hollow shapes while adding original touches and offering customer-specified scale lengths. Recurring models include the Rigmor lap steel (23" scale, mahogany and ebony, Lollar P90), the Solveig offset (available in 25.5", 26", and 28.5" baritone scales), and the Vera semi-hollow. Instruments are typically fitted with boutique pickups and hardware selected per build.

Kaldhol's client list includes players from Norwegian acts such as Jaga Jazzist, Madrugada, Wobbler, and Big Bang, alongside studio and session musicians around Oslo. The brand's reputation sits within the Scandinavian boutique-luthier scene rather than mass production.

Oslo Instrumentfabrikk has 4 products cataloged on Equipboard, including Solid Body Electric Guitars, Semi-Hollowbody Electric Guitars, and Electric Basses.