A Version 4 UUID Implementation
this isn't much shorter but instead of 

; add the hyphens between each block 
data: insert skip data 8 "-"
data: insert skip data 4 "-"
data: insert skip data 4 "-"
data: insert skip data 4 "-"

head data


you could write

parse data [8 skip insert "-" 3 [5 skip insert "-"] to end]
data


And you don't need a for loop

loop 30 [print makeuuid]