hi, i have started using sandbox today to get a 3d-demo for a project im working on (creating an anamorphosis in RL), long story short is it possible to insert an image in a sandbox-map? i've experimented with textures but my picture has to be at least 50x50 blocks big. so i cant paint each one with a different texture.
i'd like to use the map as an walk-in simulation of the future project in real life. any other approaches/ideas are welcome

btw im not into 3d-software, i tried to use blender to make a huge "board" with my picture on it but i failed, and i got no time to learn blender first.
thx for any help, ideas or workarounds!!!
btw: im sure this was asked before, i DID use the search-function but couldnt find something about my problem so if this is a re-post and im just to blind or dumb or stressed or whatever, im sorry!