(2) the shadow is made of paper, which can be pasted on the computer or purchased directly from the general painting tool store. Some cartoonists also use sketches to make grids.
In my opinion, you can use a duckbill pen or a student pen.
The black box is hand-painted. I am also a fan of April. I have read her paintings carefully. If you look closely, you can see that the boundary lines of some squares have exceeded the parts that are not coated with correction fluid, so I conclude that they are painted by hand.
April is definitely hand-painted. If you don't believe me, you can compare it with April's paintings (in April, I had a computer painting "Morning Star in Midland" and "Fairy Tales in Winter"). If we compare them, we can see that computer painting is not as meticulous as hand drawing.