My story
I am Brendan Koster, an urban planning engineer and data analyst. Electronics and 3D printing are my hobby, mostly for my boat.
How it started
In 2020 I had an older sailboat on which I had put the mast and sails myself. On top of the mast belongs a light that can shine all white or in three colours. Those were expensive, and for little more than double the price I could buy a 3D printer and print one myself. My mother used to say: “Brendan can do anything if he wants to.” So this had to work out.
The first lamp was too low and wide, and came loose from the glass plate. The second, taller and narrower, came out right. The printer has hardly stood still since. Since January 2025 I print on a Bambu Lab A1 mini and an A1, and I mostly draw in FreeCAD. TinkerCad remains handy for something quick or for first steps.
In late 2022 I had a steel boat. I worried about damage around the deck feed-throughs and wanted a message on my phone if the boat took on water. I could not buy such a system, so I started studying Arduino and Raspberry Pi. With no prior knowledge I began what is now BKOS.
It grows slowly, because I do not spend all my free time on it. Roughly I do two big improvement rounds a year: experimenting at the end of the year, refining at the start of the next.
Small projects
My Christmas cards of 2024 (a tree, also practice in small soldering) and 2025 (a sleigh on a colourful circuit board) are favourites. What it will be for 2026 I am still working out.
Timeline
First 3D printer and a self-printed masthead light.
Bilge alarm for a steel boat, the beginning of BKOS.
First steps with breadboards, microcontrollers and logic chips.
First own circuit boards, designed purely for function.
Enclosure, two-part circuit board and fuses on the board. Focus moves from sensors to switching.
More features and a new screen as controller: the 7-inch ESP32-S3.
What I can do for you
Is there something on this site you like? I have usually put the files on GitHub. For non-commercial use you may download and print them or order them from a PCB manufacturer or print farm. Want exactly that design with a small change, such as another name? I am happy to adapt it for a small fee. I can also handle production, or have it handled.