The video below was created by Meindert Kuipers to demonstrate his MLDL2000 interface for the HP41. The video is also available on youtube.
It is a demonstration of the various possibilities of the MLDL2000 which is using an mbed module for advanced I/O like networking, USB connectivity, extra in/out ports, … You can clearly see in the video that the project is manually wired on a breadboard which makes it unique on one hand but not easy reproducible on the other hand. The author promised to create schematics and pcb layouts, most probably only if somebody is interested in his work. He also gives credit to Marcus von Cube for the network functionality and some Java visualisation applets.