Thank you for the designs I have gone for the UFC and 2 screens as a desk setup. I modified your original DDI Left and Right so that you can bolt them to the UFC so they attach as one unit. Minimum of 20mm long bolt required.
I hope you dont mind but I will upload them for anyone who wants them in the future hopefully they will be helpful to someone
Left DDI with holes v1.stl
Right DDI with holes v1.stl