There must have been some evidence (whether direct or not) that Vasa had mouses on the stays. The Vasa museum rig plans show them. I also included them in my model. I just took the stay and wrapped it with smaller diameter line where I needed the mouse to be to create the raised effect.
Hi Ulisis and Clayton, for my Soliel Royal build, I made the mouses with two part epoxy putty, I think I used Milliput. After you mix the putty with your fingers, apply it to the stay and shape it into a mouse. The major challenge I had is to apply the right amount BEFORE it sets because I discovered that you cannot grind it later (you will cut or damage the stay). You can paint it.
The stays themselves did not survive, so our reconstruction of the mouse is based on images and models, as well as the later process of making a mouse. We can show exactly where the mainstay was wrapped around the head of the mainmast, since there is a notch for it in the edge of the lubbers hole in the top. All of the associated details in the mast and top, as well as the deadeyes for the lower end of the stays, indicate that the stays were rigged in the conventional fashion of the time.
In a real eye and mouse, the mouse is made up of a large number of small strands woven together over a lump raised on the stay. Olof Pipping, who rigged Vasa in the 1990s made one mouse and eye just to practice before doing the final one. The are of the mouse thus does not show the lay of the stay, but a woven exterior which extends above and below the lump.