I want color e-paper that can show large paintings, like 30” x 40”. When is that coming out finally !!

If you're happy with grayscale, biggest from Good-Display[1] offers 25" x 33". If you want bigger, you'll probably have to wait until Samsung's new 75" EMDX panel[2] becomes available for purchase.

[1] https://www.good-display.com/product/452.html

[2] https://news.samsung.com/global/samsung-showcases-color-e-pa...