I've already create the Masonry Grid without problems but since 3 days the thing that stopped my job (and created problems with my client ) it's the possibility to browse Galleries into the Artist Page.
As you suggested I've created Galleries (collection) for each Artist but it doesn't work when i try to use the Layout below:
I see where you "stuck" and I know how to help you. Please, could you re-create Gallery collection? For be able to show all 3 type of galleries you need all the images for one Artist inside one collection and each image should be a separate item (not the way I suggested first).
Let me know when structure will be done and I will be able to show you next step
Also some tips: 1) You don't have to upload the same image few times with connecting it to different categories. 2) Category ALL - not needed, remove it. All images without filtering by category will be available in one dynamic list.