Jan

@jflessau.bsky.social

95 Followers 133 Following

Software dev for health care products by day, side project hoarder by night. 🦀 rust | 🎾 padel | 🎲 dnd | 🖨️ 3d printing 📍 Hamburg, Germany Website: https://jflessau.com GitHub: https://github.com/jflessau Mastodon: https://hachyderm.io/@jflessau

Thermal printer with a piece of paper coming out with the text 'Hello World'. On top of the printer is a 3D-printed crab, the mascot of the Rust programming language. In the background, wires connect the printer to a Raspberry Pi Zero 2 W.
Average Vehicle count per 15 minute time bucket over 24 hours from several car counting sensors in Hamburg, Germany. The line chart looks much smoother than the price chart just one big wave starting at 3:20 with its peak at 12:30.
Line-chart of average Diesel, Super E5, Super E10 prices over 15k gas stations in germany for one day. Seven sharp increases followed by slow decreases.
Line chart of Diesel prices of one gas station for one day. There are several sharp increases, followed by slow decreases. Cycles are about 3-4 hours apart from each other and there are not such cycles at night.
Line-Chart of fuel prices of one gas station in germany, showing Diesel, Super E5 and Super E10, all on the rise from around 1,70 € to almost 2,10€ per liter in the past few days, while they were relatively steady the three weeks prior to that.
Terminal output, starting with uninteresting headers from CURLing a site, followed by the LLMs output. The original LLM output is in german. Here is the english translation: Here are the next collection dates from the waste collection calendar, sorted by date: 12 February 2026: ⚪🔵
 13 February 2026: ⚫
 20 February 2026: ⚫🌿🟡
 26 February 2026: ⚪🔵
 27 February 2026: ⚫🌿🟡
 6 March 2026: ⚫🌿🟡
 12 March 2026: ⚪🔵
 13 March 2026: ⚫ Emojis: ⚪: Blue paper bin ⚫: Black residual waste bin
 🌿: Green organic waste bin
 🟡: Yellow recycling bin/bag Please note that the collection dates are listed starting from the current date (11 February 2026).
3d printed case of my cyberdeck. With a 3x3 key pad, a small and a large OLED and a physical button.
The display on my retro cube showing „this is dog“, which is the part of a message that fits on the screen. If this were a video, you would see the text line moving to eventually display all characters.
3d printed housing for a raspberry pi zero w and an OLED, showing a text message: „Low-res, high vibes“.
A rectangular 3D-printed case for a Raspberry Pi Zero W, an OLED display, and a dial for navigation on the top. When you turn the dial, the display cycles through different views: 1. Date & Time 2. Weather Data 3. A short message displayed across the screen The box is approximately 10 cm wide, 5 cm deep, and 5 cm high. The display is on the front, while the navigation dial is on the top and rotates along the Z axis.
Screen recording of a CAD software view showing the individual parts of the cyberdeck, including: a power bank, Raspberry Pi, mini OLED display, large OLED display, a physical button, a 3x3 keypad (essentially a numpad), and a handle mounted to the case similar to those found on kitchen drawers.
Line chart plotting diesel, E 5 and E 10 fuel prices of two gas stations for one day. Prices for all fuel types and both stations are, based on the 6-ish price spikes, very synchronized.
A screenshot of a website showing a search bar for location and zip code at the top, a map of Hamburg in the middle, with pins and prices for petrol stations, and a list of petrol stations below the map, showing the first two with their name, zip code, price and the time of the last price update. It’s 1,49€ at 21:20 for the first station and also 1,49€ at 21:00 for the second one. The petrol station names are: Raiffeisen Energie Nord GmbH at zip code 22952 and the second one is Calpam Express 6-22h Tanken at zip code 22941
Screen recording of a 3D model rotating in the animation software Blender. The model features a 16:9 7-inch OLED display, a much smaller, 128x60 px OLED display above it, a 3×3 keyboard (essentially a numpad), a dial, a switch, and four buttons. There is also a speaker on the side, with a Raspberry Pi and a power bank hidden inside. On the left side, there is a handle for easily grabbing the whole device.
A screenshot showing a bulletpoint of a blogpost with the text: "If DIR is unset, rm -rf $DIR/ becomes rm -rf /. Using set -u can make bash error when encountering unset variable."
Video of a computer screen with a bug trapped between the transparent glass and the background lights. It is following a jiggling mouse cursor. At least for a while.
3D top-down view showing a low-poly ground with a character moving across it. The character is a simple ball with a smaller ball orbiting it, indicating the aiming direction. The character moves through a stone arch and shoots bullets in various directions.
A screenshot of a web app in mobile portrait mode. The navigation bar at the top shows the title "McSprit," followed by an icon of a fuel nozzle and a search input field. Below the navigation bar is another bar displaying the selected location (Hamburg, zip code 20354, Germany in this case), the selected fuel type (Super E10), and the distance (5 km) for the radius search. Below that is a 2x2 grid showing the number of gas stations (12), the average price (1.59 €), the minimum price (1.45 €), and the maximum price (1.72 €). Below that is the headline "Tankstellen" ("gas stations" in English) and a list of gas stations with their name, zip code, current price, and distance. The list is filled with mock data (gas station 1, gas station 2, etc.).
An e-ink display in a 3D-printed frame on a desk. It shows a turtle on the display.
Hacker News screenshot of the post about Material 3 Expressive. First sentence of the first comment is highlighted: „How did these clowns manage to make my mouse cursor laggy?“ Rest of the comment: „It is incomprehensible for me to live in such a big bubble with such a big paycheck and then spend zero brainpower on systems without graphics acceleration. This is extremely bad engineering and these engineers should be called out for it. It takes a special kind of person to deliver this and be proud of it.“ Info about the posting itself: Title: Material 3 Expressive Website: design.google 180 points Author: meetpateltech 9 hours ago 292 comments
A website displayed in portrait mode. The navigation bar at the top includes a back button on the left, the username "jflessau" in the center, and a settings icon (cog) on the right. Below, the headline reads "Road Trip." Underneath are two buttons: "Copy Invite Code" and "Settle Up." Below these is a list of members, currently showing just one: "Joana Doe." Further down is a history of expenses and transactions. Transactions indicate who sent money to whom. Expenses have a title (e.g., "Gasoline"), a user count showing how many people the expense was split between, and an icon indicating the split type (split evenly or custom amounts per user). At the bottom of the page is a button to delete the tracking project.
3D-printed base for DnD miniatures, projecting an adjustable field of view cone.
The entire video is just one still image: a dark blue background with a radio and the text "SkyWave Radio" below it.
A screenshot of connected workflow steps. Some steps are omitted, such as the one querying the Hacker News API. The steps shown work with the text data retrieved from the API: 1. Ask ChatGPT for a summary. 2. Use custom JavaScript to calculate the number of characters in the summary (TTS is expensive, so we're only sending texts below 20k characters to the TTS API). 3. If-else condition: A) text is shorter than 20k characters, B) text is longer. 4. Text-to-speech (branch A of the if-else). 5. Send email (also branch A of the if-else). Branch B is never used.
Screenshot of pixabay account statistics: 13k likes, 8 million views, 5 million downloads
Postgres Ultras fan shirt design featuring a muscular elephant framed from head to shoulders, with the text "POSTGRES ULTRAS" below it.
Screen video in portrait mode. The first view (list view) shows a list of habits ("Drink water," "Go for a walk," etc.) as rows and the dates of the past five days as columns. A checkmark indicates habits completed for that day. The second view shows the detail page of a habit with its name and options to: 1) go back to the list view, 2) rename the habit, and 3) delete the habit. Below that is a grid of dates (one week per row). Days on which the habit has been completed are highlighted. The third view shows a text box with some JSON (a format for text data) that represents the state of all habits (their names and the dates they have been completed). Users can copy and paste this text to export their data. The fourth view shows an empty text box. Users can paste exported data here to import it.
Postgres: populate table 10 s count all users 38 ms get ten users with most coins 30 ms sum of all coins from all users 25 ms Surreal: populate table 65 s count all users 6 s get ten users with most coins 8 s sum of all coins from all users 8 s
A bulletpoint list. Here are all the points on it: • Browser extension to read text in a user-selectable voice. • Availability zones for everything from take-away food and car sharing to grocery deliveries, with notification emails if something new pops up in your area. • (Web) app for splitting expenses. •Pen & Paper Character Tinder: find the perfect match for your next campaign/one-shot. • Some fun GitHub actions, like ordering food via Uber on a new release. • Control Philips Hue lights with a VSC extension. • GitHub contribution widget for Android (the only one I know of is kind of ugly). • Meow Meow Beans app (in case you like the series "Community"). • (Web) app for creating/playing text RPGs.
Two tables, one for Postgres, one for Surreal. Postgres: populate table 10 s count all users 38 ms get ten users with most coins 30 ms sum of all coins from all users 25 ms Surreal: populate table 65 s count all users 6 s get ten users with most coins 8 s sum of all coins from all users 8 s
A screen recording of a desktop GUI. First scene: Setup view for a new postgres connection. Second scene: A list of connections in the sidebar, next to a dropdown select for the database schema. Below that a list of tables or views in that schema. To the right of the sidebar is just empty space until the user clicks on a table to open it in the main view. Once more than one table was opened, new tables show up in new tabs in the main view. The table view contains the tables rows and columns. The tables are filled with dummy data (username = john doe, etc.). Thats it :)