Yes, there is a 3D printable cuvette holder which you can use. It is a SolidWorks part file, but I need to save a stl file instead. It's currently located here: https://github.com/Photosynq/PhotosynQ-case/tree/master/MultispeQ/MultispeQ%20Attachments/Cuvette%20holder . I'll work on getting the stl file in there.

You can see how it works in the blog here:

http://blog.photosynq.org/fun-photosynq-cuvette-holder/

Unfortunately at this point it's not easy to move back and forth between 'leaf mode' and 'spec mode' with this attachment because it requires some recalibration when you put it on or take it off. The next version (v1.0) which will be out Spring 2016 will work for a spec and a leaf without modification or recalibration!

Thanks.