I'm on the record as not being a big fan of the Marvy LePen, much to my friend Ana's dismay. It is by no means a bad pen, I just feel that there are many similar pens that do a much better job than the LePen does. That made me hesitant to try out the Marvy LePen Technical Drawing Pen but I am glad I did since it is quite good.
It falls into the same category as a litany of other drawing pens like the Sakura Pigma Micron, Uni Pin, Staedtler Pigment Liner, etc. It is a crowded group for sure, making it hard to stand out. But I like how the LePen Tech has performed so far and would say it ranks highly among its peers.
What I liked the most about it is despite the super fine tip I went with (the 0.1 mm in this case), it felt durable. My lines were crisp and clean, and while I haven't put this pen through the ringer that an artist would, it held up well. The barrel is larger than most other similar pens but I didn't find that to be an issue. In fact, it was downright comfortable. You can see the size comparison next to a Sakura Pigma Micron below.
The Marvy LePen Technical Drawing Pen looks like a keeper to me. I plan on ordering one or two other sizes to test out and if that goes well may add it to the regular rotation of drawing pens in my arsenal.