Congrats to Widow!
If the molt is damaged, or if I didn't get to pull it out of the cage before it dried, I just throw it away, but I save the best ones in shadowboxes: Be sure to pose the molt nicely before it dries, then little dab of hot glue on each foot and press it gently but firmly to the shadowbox back. Just be sure to check the shadowbox dimensions carefully before purchasing: many are too shallow.
This is the shadowbox I used for the above image; unfortunately, it's no longer available for purchase from amazon, but perhaps you can find something similar.
https://smile.amazon.com/gp/product/B07TFRQV4R/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I also use a little hot glue to keep the top of the cephalothorax in place, but you have to be really careful with that: it's fragile and cracks easily.
