Add a magnetic mount for the 10cm mount from B10x, B1x etc. so it easy to add Filter, grids etc. to the flash. So it is possible to use gels with a softbox.
Make a thin border to not loose any light and that it is not bigger than 10cm.
I think it is a great idea to make grids for deep umbrellas. I love deep silver umbrellas but i would like to make a light more focused. Mounting system for grids on clic softboxes will fit perfect!