Welcome to the Forum @Deb321 
While Seamly is meant to be optimized for garment drafting, it is quite usable for any flat-pattern drafting. I myself have used it to draft a purse, as well as several craft items. I remember a while back someone using it for a backpack pattern, @Grace has used it to draft, I think it was a gift-box to be constructed out of card board. Most recently, I used Seamly to copy a doll pattern which I had previously sketched out by hand.
Here you can find the topic with my purse draft: Christmas Purse!
Here’s the topic where the tutorial on the backpack was linked: Simple Backpack Pattern
I hope this provides the pointer you were needing! If not, any further questions/clarifications are also welcome.
