Notebook · Hardware

A card reader you could not buy.

From a thought by a lake to a device on the wall: sketch, Blender, 3D print, sanding and paint, aluminium plate, firmware. And the app that clocks in with it.

To the project

Start

The idea came in the mountains.

No brief, no screen. I was out walking, forest, mountains, a lake below. That is where I drew the sketch: a flat box for cable and electronics, and on the lid a landscape like the one in front of me. The footage from up there and the sheet with the sketch are here.

Model

From paper into Blender.

The housing is not built in CAD but in Blender, that is where I feel at home. The sketch gets rebuilt edge by edge until radii and fit are right. The videos show two pencil lines turning into a body.

Structure

Four parts, four jobs.

The device is not a block, it is a stack. Scrolling pulls it apart.

Aluminium plate

Lid

Frame

Base

01
Aluminium plate
Cut to size, sits in the lid. The film comes off last.
02
Lid
Plastic, carries the landscape from the sketch. Surface and technique fit together here.
03
Frame
The part you see. Hence the most demanding paint, with the notches in it.
04
Base
Cable management and the seats for the two boards.
Scrolling pulls the parts apart

Tool

The add-on that came out of it.

Modelling the landscape on the lid by hand was too slow for me. So I wrote a Blender add-on: drag a landscape onto a surface, add a logo, done. It also places the notches and cable holders every housing needs. One device turned into a tool for the next ones.

Surface

Print, sand, paint. Repeat.

Out of the printer comes a blank with layer lines. Then sanding, filler, primer, automotive paint, sanding again, paint again. The frame gets the most work because it is what you see. Tap through the rounds or drag the handle between raw and finished.

Round 1 / 5 · Raw from the printer

Assembly

Everything in its place.

Print the base, seat the two boards, route the cable, put frame and lid on. The aluminium plate for the lid is cut to size, its protective film stays on until the very last step. Peel it off, and the thing is done.

Firmware

The code that reports the card.

Inside sits a small controller with a reader module, running firmware I wrote myself: read the card, report it to the server, keep itself up to date. Here I show how I program it and how the device is used day to day.

In the shop

Tap the card, done.

The reader hangs next to the iPad at the till. Card on, and the time clock instantly shows the name and one big button. On its own the device would be a pretty case, the app behind it makes it time tracking for two shops. Try it here: drag the card onto the reader.

Card0042

Drag the card onto the reader

4.11.2026

…

Shawarmery: Zeiterfassung mit NFC, Zeiterfassung: Hardware, Firmware & Web

The app behind it

Time clock with NFC

Tap the card, name and hours appear on the iPad at once, one button confirms. The owner sees both shops live. Without this app the reader would just be a case.