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The original was posted on /r/homeassistant by /u/NoviSense on 2026-07-19 05:24:16+00:00.
Hey all - heads up right away that this is my own project, so this is a self-promo-adjacent post. I'm putting it here because you're the people most likely to find the holes in it, and I'd rather hear them now.
Background: I'm an electrical foreman. I've wired up a lot of nice homes - good millwork, tile, stone counters - and then watched a clunky remote or button get slapped on the surface at the very end. It always bugged me. So I built a switch that hides behind the finished surface instead of sitting on top of it.
It's a capacitive sensor that mounts on the back of the material, so there's nothing visible on the surface at all. On my prototypes it reliably registers a touch through up to ~60mm of drywall, tile, glass, wood and any non-metallic surface. You tap the material and it fires.
The part I figured this sub would care about most - it's local-first:
- Reports into Home Assistant over MQTT with auto-discovery, so entities show up on their own.
- Also speaks Matter.
- No cloud account required, no subscription, no app-in-the-middle. If your internet's down it still talks to your local broker / HA instance.
Honest caveats, because I'd rather you hear them from me than catch me on them:
- It is not ESPHome. It runs custom ESP-Matter firmware, and the HA hook is MQTT auto-discovery rather than the native ESPHome API.
- Still prototype stage - validated on the bench, not a shipping product.
- Through-material sensing needs a short guided calibration per install (material and thickness vary), which the device walks you through with audio prompts.
- I can't call it "Works with Home Assistant" - that's a formal certification I can only pursue later - so I'm describing the actual integration, not claiming the badge.
What I'd genuinely like feedback on:
- Would you put a no-moving-parts capacitive pad behind your wall in place of a physical switch? If not, what's the dealbreaker?
- Does the firmware choice (MQTT auto-discovery vs. ESPHome) matter to you as an HA user?
- Failure modes I should be stress-testing before I commit to a production run - false triggers, humidity, something heavy leaning against the wall, kids, pets, etc.
Happy to get into any of the technical detail in the comments. I'll drop a link to the build and waitlist in a comment rather than the post body so this stays about the feedback, not the sell.