This is a fifteen digit seven segment display made form a PCB with SMD LEDs on it and a 3D printed frme to form the segments. A diffuser is needed over the top of the frame to even the light over the segment.
This construction is similar to larger displays that can be bought, it's just a bit smaller and more dense in terms of the number of digits. The PCB is about 60mm wide and 14mm high. The PCB was hand assembled and then soldered in a reflow oven, but it should be possible to get it assembled by a PCB manufacturer. The LEDs are red. There's no filter. The display looks a lot better in real life than in the photos, it's very difficult to photograph this display. The diffuser is a piece of masking tape stuck over the display at the monet, this also holds the frame on to the PCB, That coud be tidied up.
The frame is 3D printed from resin. This is a white version (which doesn't work):
The white resin doesn't block light well enough, a black resin version is used on the frame attached to the prototype.