Where is it?????

Few days ago I saw a great step by step guide, where someone is using a rapidograph type ink pen for shadow areas of a landing gear, and I spent 2 hours yesterday trying to find it again. I think it might be in start to finish section or painting or weathering, or.... I'm not even sure if it was on this forum anymore! Does anyone know what I'm talking about and where is it??

Gak, I remember someone posting about these pens and have been looking but am unable to locate the thread with the post. Will keep trying.

Thanks Aaron! If you find it let me know! I gave up. I used them my self just today. For now they work like a charm, but I would still like to see that guide...