Hood ống kính ren 49mm low profile

This is a low profile 49mm threaded compact lens hood/shade with a few versions. 

I recommend printing at 0.10mm layer height in PLA for best results with the threads, but it should be fine at 0.15 too. Fuzzy skin modifier makes it look nice IMHO - just make sure to use a height range modifier or something so you don't make the threads fuzzy. 

About the different versions:

Version 1 is sized to replace the MH-RC 49 hood for the Pentax DA 40mm f/2.8 Limited, but should also work on f/1.7 and f/2 Pentax 50's [A, F, FA] (and GRIIIx with an adapter)

I've been using a knockoff MH-RC49 on my GRIIIx and with my A 50 f/1.7 for compact shade and protection.

If I did the math right, the size of the opening on that official hood is almost exactly the right size to also work on the F/1.7  Pentax 50s without cutting off the bokeh, but for some reason they're weirdly expensive and third party knockoffs are just not on eBay right now? 
So I made my own

Version 2 (pictured) is sized for the f/1.4 50's [A, F, and FA]

This version just has a Bigger Hole so it doesn't cut off the bokeh on the faster 50's. Still offers decent shade and protection while being very compact. 

Version 3 has a way-too-tight rectangular opening, intended for shooting stopped down

This one will probably cut off the bokeh wide open on any of the 50s, it's intended specifically to offer the most shading and protection possible for shooting at f/2.8 or tighter, the point at which they all start becoming most sharp imo. 

I used this blender plugin to make the threads more easily:
https://makertales.gumroad.com/l/PrecisionBolts