Easier to print (but longer) simple piston pen

This is almost same simple pen https://www.thingiverse.com/thing:2969193 (in 2 sizes) but made for better printing (which made it longer, 45 degree threads and 45 degree surfaces) also now available design for Peter Bock nib modules (as well as old number 6 nib with feeder and unknown reform nib module).

Also cap-thread now put on the same level with body which make it easier to hold, cup is tight and it is easy to polish the body.

Here also tested technology of making ink-window. But ink