The Mini•Dub is a smaller version of the 4TW by jonyfraze, and the primary difference is how the edges are mostly straight.
The VM6R offers multiple layouts and can be ordered as a case or preassembled. It also features both Iris and Lolli tech.
Chibico by Acrycade Gear is a mini stickless controller that should be able to fit into a back pocket of a pair of pants.
The QRD Maestro S3 can either work wirelessly or with a wired connection, depending on your preference when you play.
The Skullbox Leverless Arcade Controller is smaller & thinner than average and has proprietary SkullCaps that mimic the Sanwa feel.
The pandemic inspired the inception of Wood Tier Customs as a woodworking studio that makes enclosures, sometimes prebuilt.
The Ekkusu Fight Controller is a leverless controller that is thicker than average, allowing it to use premium buttons like Sanwa.
Panda Fighting offers a variety of all-button controllers in different layouts and sizes, such as this controller that has 16 buttons.