Underset: Compact Wireless Spartan Split Keyboard with Considerable Pinky Offset

“A spartan split keyboard with some considerable pinky offset: Underset by humanplayer2.” That one-line summary from KBD.news nails the tradeoff Rasmus K. Rendsvig built for: compact footprint and a pronounced pinky cluster on a 52-key, wireless split that deliberately keeps electronics out of the print-facing surfaces.

KBD.news ran the project in Keyboard Builders’ Digest as KBD #207 on Tue 24th Feb 2026, crediting Rendsvig under his Reddit handle humanplayer2. The post carries tags including split, wireless, open-source, PCB, MX, and hotswap, and the author also posted design notes and build context across r/ErgoMechKeyboards, r/MechanicalKeyboards, and r/3Dprinting.

Design intent is explicit: Rendsvig calls Underset “spartan” and says it was inspired by the Silakka54 while remaining in the family of 4-row column-staggered split keyboards that includes Dygma Defy, Elora, Go60, Iris, Lily58, Sofle, and ZSA Voyager. Functionally the board is compact but not toy-like: the layout is described as “52 keys (6x4+3-ish)” and the model “includes a numbers row,” a deliberate choice tied to a PCBWay sponsorship built around ThinkPad keycap MX stems.

Ergonomics are where Underset stands out. KBD.news writes that the board is “a spartan 52-key column-staggered split keyboard with aggressive pinky stagger and keys partially underset the ring column for a three-key curved pinky cluster.” That aggressive pinky offset creates a three-key cluster that visibly undersets the ring column, a geometry aimed at reducing lateral reach for common pinky keystrokes while keeping the overall deck small.

Hardware choices aim for maker-friendly assembly. The project lists MX switches with options for hotswap or soldered mounting and name-checks both RP2040-Zero and nice!nano v2.0 controllers. As the post and Rendsvig’s Reddit notes state, “Both RP2040-Zero and TRRS underset the switch plate for simple cases that still isolate the electronics.” The PCB is reversible, includes an underset TRRS jack, and the case is intended to be 3D-printed so “both top and bottom of cases could be printed lying on a 3D printer plate.” Firmware support is Vial and QMK and the design was produced using Ergogen.

Context on development: Rendsvig explicitly tied the project to a PCBWay offer to sponsor a ThinkPad-stem project, writing, “So when PCBWay offered to sponsor a project based on ThinkPad keycap MX stems, I thought I'd combine those two features in a new-to-splits friendly format, i.e., in a model that includes a numbers row.” KBD.news also shows a photograph placeholder labeled “Pic:” and a Resources section, while the author encouraged the community with a simple line: “These communities are great places to ask for more personalized advice and see what other Redditors are using.”

Missing specifics remain concrete and important for builders: the sources do not state the wireless protocol, battery type or charging method, exact BOM, or current file and PCB availability. Confirm which controller is final, whether wireless means Bluetooth or a radio dongle, and where STL, PCB, and keymap files are published by checking Rasmus’s posts on r/ErgoMechKeyboards, r/MechanicalKeyboards, and r/3Dprinting or the KBD.news Resources for KBD #207. Underset is a purposeful minimalist split for builders who want easy 3D prints and a pronounced pinky cluster rather than a feature-heavy luxury board.