I just bought this toilet for my camper and saw they sell a plug like this for much more than I wanted to pay so I made one and didn't have to pay shipping.
This is a plug to seal off the urine drain on the Trelino Evo model toilets but iit may work for the others too. This is to aid in keeping uring smells from creeping out of the toilet. There already is a membrane that should also assist with the smell/splashing but why not add a little extra piece of mind?
I would recommend printing in a bright color so you remember to remove it before using the toilet.
The author marked this model as their own original creation.