Grapnel Cap: A Thumbstick Extension Designed for Funscripting

While creating Funscripts with a game controller, I ran into two recurring issues:

  • Pushing the thumbstick with my finger became tiring after a while.
  • The thumbstick’s short travel made precise positioning difficult.

To address these issues, I designed Grapnel Cap.

Unlike conventional thumbstick extenders that simply increase thumbstick height, Grapnel Cap also changes the direction in which force is applied. The goal is to make long editing sessions more comfortable while allowing finer thumbstick control.

The design uses a two-piece snap-fit construction that encloses the thumbstick without requiring adhesive or permanent modification. When properly installed, it stays in place without damaging the original rubber surface.

Confirmed Compatible Controllers

  • DualShock 3 (PS3 Controller)
  • DualShock 4 (PS4 Controller)
  • DualSense (PS5 Controller)
  • Xbox 360 Controller
  • Xbox One Controller
  • Xbox Series X/S Controller

Getting the STL Files

The STL files are available here:

Beyond Blackwall

This is a digital download containing STL files only. No physical product is included.

A 3D printer is required to make the parts. PETG is the recommended material because it generally provides a good balance of toughness, durability, and ease of printing.

If you have suggestions for additional controller compatibility or improvements to the design, I’d be interested to hear your feedback.

Here are my other projects

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I recently added support for the PS3 controller and the Xbox 360 controller.

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