Okay just two girls, one robot and one mecha(?) left unannotated for now.

Bingo, figured out who those two girls are.

They are gyaru*-lite characters with an interest in building Gunpla kits, who first appeared in Ishiyumi-sensei's Goddess of the G-Spring series. They also make some appearances on their own afterwards in independent shorts.

They are two highschool girls with an interest in mecha and robots, from Ishiyumi's Girls Who Get It series. They also have an interest in Gunpla, and some of the later shorts in the series featuring them building Gunpla. The series also crossovers with the Goddess of the G-Spring series, so both these girls also make appearances there.