My goal here is to create a filter holder for my 49mm filters. After printing today and testing, it holds my +2 and +4 close-up filters very well. No slippage, no hint that anything would fall off. (The macro filters provide little benefit except being able to close focus and the Lytro's longest focal length, down to 5 1/2" at 51.4mm.)
The real goal is for a polarizing filter and after printing the 49mm holder I realized I only have a 52mm, and above, filter. So, off to design and print another. If you have any questions, please email.