These things are “built” by Mum experts, it is a cottage industry. Although the details are hidden from dads it is rumored that these masterpieces can set you back in the 3 figures range.
The size and level of detail are how these are measured. Every one is custom and usually has little details that say something about it’s wearer. Notice the Bass Katie’s bear is playing. That is a genuine Fender Bass once played by Peter Tork of the Monkeys.