Eight Interlocking Rings (Origami to Astonish and Amuse)

[Aleburzyn]

I'm having problems with step 19 (stretching) of this model, also i have probles finding a good paper for it, but that one can wait.
I don't understand how to do the stretching properly, just pulling the points doesn't solve the prblem at least for me. I'm thinking that maybe it's some kind of elias stretch or similar, but there are'nt any references to the inner creases, any photo showing them would be of great help .
Thanks.