It's been a while since I last saw this fella! Another remarque, now with Man-Bat as special guest!
These were the very first attempts at Walter. Before l got @JamesTheFourth description l kinda imagine him like Ron Howard, hence the one with a cap 😬#TheNiceHouseOnTheLake
About the symbols! These were the first ideas l came up with.. some changed a bit in the end, as did the designations.I decided later to use that second image as a grid, you can decompose it to form all the symbols.