Tablet Wall Mount

overview

My Home Assistant kiosk is a Samsung Galaxy Tab A7 Lite on the wall next to my intercom. It sits in two 3D-printed rails I designed in OpenSCAD: the tablet drops in from the top and lifts straight out whenever I want to use its camera. No screws, no top clip, just adhesive tape.

Then I stripped the tablet down to only what the kiosk needs, and set it up so every photo it takes lands on my homelab's SSD on its own.

the mount

Two mirrored C-channel rails hold the tablet by its left and right edges in landscape. Each rail is a back plate that takes the tape, a short shelf the tablet stands on, and a lip that wraps over the front bezel. I used two corner rails instead of a full-width cradle so nothing clashes with the intercom beside it.

fits by design: The tablet is 212.5 × 124.7 × 8.0 mm and 371 g. Each rail adds 0.4 mm of slop so it slides in without scraping but doesn't rattle.

easy to grab: The rails are 105 mm tall, shorter than the tablet, so the top edge sticks out and I can pull it straight up.

room for the charger: The side wall stops at 46 mm, below the USB-C port, so the cable rides up and out with the tablet instead of catching. A slimmer bar continues above it.

nothing covered: The front lip has a notch from 42 to 84 mm for the front camera and light sensor, which doubles as a finger grip. There's also a relief cut for the rear camera, in case the rails ever get taller.

thicker for PLA: The lip and shelf started at 2.5 and 3.5 mm. I bumped them to 3.0 and 4.0 mm before printing in PLA.

The whole model is parametric: every dimension above is a variable, and one setting switches between printing both rails, just the left, or just the right, with an optional ghost of the tablet to check the fit. With those values, the tablet's face sits 11.6 mm off the wall, the rails are 213.3 mm apart on the inside, and each rail's footprint is about 25.5 × 109 mm.

printing and mounting

Printed on a Bambu Lab A1 in white matte PLA: 0.16 mm layers, 4 walls, 25% gyroid infill, supports on the build plate only. To mount it, I used the tablet as the jig: slide both rails onto it, put tape on their backs, press the whole thing against the wall, let the tape cure, then slide the tablet out. The rails end up exactly as far apart as they need to be.

debloating the tablet

Out of the box the tablet came with a pile of Samsung and Google apps that a wall kiosk doesn't need. I removed them over ADB from my Mac, without rooting it:

first pass: Universal Android Debloater's "Recommended" list.

second pass: Everything else I didn't need got pm disable-user --user 0 first, so I could check nothing broke, then a pm uninstall --user 0 sweep. That removes the app for the user without touching the system partition, so a factory reset would bring it all back.

no Google: The Play Store, Play Services and Google Services Framework are all disabled.

What's left: four apps from F-Droid (Tailscale, the Fennec browser, the Home Assistant companion app and Termux), the stock Samsung camera, and the system pieces that Android needs to function: WebView (which the Home Assistant app renders in), the permission controller, the package installer, the network stack and the media provider. The OS is set up for the kiosk too: swipe gestures instead of a nav bar, no taskbar, and the smallest screen zoom, because the dashboard's grid needs every pixel.

photos straight to the NAS

Since the tablet lifts out, it's also a camera. Termux runs rclone on a schedule and copies everything in the camera folder to a folder on my homelab's SSD, over SFTP inside my tailnet, so it works from anywhere and nothing is exposed publicly.

it's rclone copy, not sync: the copy is add-only, so deleting a photo on the tablet never deletes it from the NAS. and since that folder is on the SSD, the nightly snapshots keep old versions too.

construction

OpenSCAD Bambu Lab A1 PLA Galaxy Tab A7 Lite ADB Universal Android Debloater F-Droid Termux rclone SFTP Tailscale

architecture

tablet camera → Termux + rclone → SFTP over Tailscale → Pi SSD → nightly snapshot

The rails are two STL files exported from one parametric .scad file, plus a Bambu project file with the print settings.

Source? The model isn't on GitHub yet. If you have the same tablet and want the files, reach out.