As noted in by oldmaninSC, “There are few choices if you need a display that can be seen from across the room.” Of course there are options that can be built with hours upon hours of work, but this project instead presents a massive display that doesn’t take a lot of effort to put together, requiring only a few connections for power and I2C control.
The setup is made out of common Hitachi 1602 LCD screens, which normally show an array of 16 x 2 digits. Given that each one of these character units costs around two to three dollars, a large display like this can be made inexpensively.
The trick here is that each individual LCD is flipped 90º, providing a screen that can reveal two numbers or letters stacked on top of each other, or a single number that stretches the length of the display. LCDs can then be stacked side-by-side for display.
OldmaninSC made a 16x2 display using this technique that shows the time, date, and day of the week in nice big letters. If you look closely, there’s even a (comparatively) tiny temperature display hidden below the colon between the minutes and seconds.
Everything is powered by an Arduino and an RTC module is used to keep accurate time and read the temperature. Code and more information is available in oldmaninSC's write-up if you’d like to build your own.