I tried to remake the pen listed above. It fits in my midori/ traveler wallet quite well and is surprisingly comfortable to use for quick notes. 

Specs= 105mm x 14mm x 3.5mm - Its about the same size as an A7 notebook

Recommend printing as oriented using ABS or PETG for longevity in a heavy infill. The most successful thus far has been at 75% using ABS.