Original sandpaper letters: cursive or print

Were the first Sandpaper Letters cursive lowercase with blue consonants and pink vowels, or did that convention evolve later? I’m a new guide starting Children’s House this fall in Austin and building my PD network — any primary sources, archives, or upcoming talks you recommend where I can learn (and meet folks who love this history)?

‌⁠‍⁠​‍​‍‌⁠‌​​‍​‍​⁠‍‍​‍​‍‌‍‌⁠‌‍⁠‌‌‍‍‍​‍​‍​‍⁠​​‍​‍‌‍‍⁠​‍​‍​⁠‍‍​‍​‍‌‍⁠‍‌‍‌‌‌⁠‌⁠‌‌⁠⁠‌⁠‌​‌‍⁠⁠‌⁠​​‌‍‍‌‌‍​⁠​‍​‍​‍⁠​​‍​‍‌‍‍‌‌‍‌​​‍​‍​⁠‍‍​‍​‍‌‍⁠‍‌‍‌‌‌⁠‌⁠​‍​‍​‍⁠​​‍​‍‌‍‌​​‍​‍​⁠‍‍​‍​‍​⁠​‍​⁠​​​⁠​‍​⁠‌‌​⁠​‌​⁠​‌​⁠​​​⁠‌​​‍​‍​‍⁠​​‍​‍‌‍‍​​‍​‍​⁠‍‍​‍​‍‌‍‌​‌‌‌​‌⁠​​‌⁠‍​‌​​⁠‌⁠​​‌‌‍​‌‍‌‌‌‌​‌‌‌‌‌‌‌​‍‌‌‍‍​⁠​​‌​⁠⁠‌​‍⁠‌‌‌⁠​‍​‍‌⁠⁠‌​​