I got this mint rOtring sec-o-mat set in a mixed lot of drawing equipment on eBay. I find the Isograph pens really elegant, but personally I only use Micronorm/Variant pens for my drawings, so I've decided to sell this on. Because these sets are quite rare, and because a new Isograph costs over €20, I figured a starting auction price of €140 seemed more than fair. If I'm lucky, this one will almost pay for the whole lot that I bought. Wish me luck!
They're lovely to work with if you want clear, repeatable lines. You need to maintain a relatively vertical pen position, but the result is perfect.
Here is an example showing two different line widths. You'll see that I messed up a bit and smeared some green ink...
Very nice... Don't think I could attain that level of consistency and precision without using a computer or a stencil. :)