My first few attempts I planted on slabs. I found this to be counterproductive to the further development of the trees. So I changed course and began planting more developed trees in grow boxes with plenty of room for growth. The result you see here. There was two more trees and replacements are being grown to be fitted in at the next repot. It is a work in progress and I'm taking the long way around this time.Excellent Japanese Maple stock but Tray way too big and Trees are spread out too much...
Easy fix...Use a smaller tray or pot and move the trees closer together creating a scene of some sort, use your imagination here...
Thanks Brian, you're right on, a bigger composition is in the works. I usually keep the roots covered, just exposed them for the pics. I dislike moss on unfinished work. I mean pieces I'm working on. It is just living in moss central, it's everywhere on everything.The box is to grow them out. That, along with the spacing indicates @RKatzin is going for a larger composition than you currently see. My only recommendation is to raise the soil level and cover those exposed surface roots for a few more years. They appear to have very nice radial distribution, and they'll thicken/age better underground. Alternately, you can let a good ground cover of moss overtake it. That helps too.