No worries, thanks for clarifying.
OK, this one is a bit complicated, and there's two ways of doing it.
The first way is to revert to a save back at the Bandit's Lair when the Bandits are still around. You need to get captured by them, escape from your cell, and re-equip your clothes. You'll get an item when you re-equip your clothes, and you can give that item to the Blacksmith, who will make it into some armour for you later.
The second way of unlocking this scene is by using the Synthesis Cauldron at the Inn in order to create the latex straps. You'll need a few materials to create it, one of which can be found in the slug caverns and from defeating slugs, and the other in the desert from fighting 'shambling mirages'.
If you don't have the Synthesis Cauldron, you need to find it from a special merchant. You'll need to head back into the Slug Den in the Jungle, and follow the path through until it emerges back outside again, where you'll find a tent. If you need more clues, let me know.
Otherwise, good luck with hunting down this final scene!
