There are modular dot shaped led matrix blocks that are basically LEDs under a cast piece of resin that guides light. They're tillable and you can drive them with an FPGA and a smart shift register based constant current driver. They're generic so you can look around online.
However this is assuming your installation will be reasonably large. If it's too big, I recommend making your own array out of discrete LEDs. They sell LEDs with a built in milky diffuser that are suitable.
For example: https://www.jameco.com/z/SBM-2388ASRG-RG-Super-Bright-8x8-Do...
However this is assuming your installation will be reasonably large. If it's too big, I recommend making your own array out of discrete LEDs. They sell LEDs with a built in milky diffuser that are suitable.