I tried to make a star by starting with a rectangle and concealing with the ‘apply mask’ tool, but when I try to put another vinyl alongside, it seems that the ‘masks’ conceal the second vinyl as if they weren’t fully transparent at all.
Is there any way to select and cut the visible portion of the star to remove the masked sections? Or a way to merge vinyls without the masked areas covering other vinyls?
I need to make my own rather than download any premade so that I can share my design after, downloading premade locks the design and not able to share end result.
Putting masked vinyls so close together can always pose that issue. I’d try making the Subaru star without masking it. Might be a little easier for you to start with.
Further to what Hotrod King said, I often use masks to create the shape or font I’m after then I’ll enlarge that vinyl group & carefully trace over it again. Takes a little bit longer than just attempting it first time without masking but it’s just one way to skin the proverbial cat 
I’ve been working with masks a lot too. What I’ve figured out so far, the best way to utilize is to make the solid shape first. Put it on the car, then create mask. Once that’s done whatever paint is at the base of the car will show through. So in this case, I’ve made this logo before so I already have it. If I paint a car chrome, then put a large black (or whatever color you want) square over the entire vehicle, load the layer group then create a mask. Once that is done you can delete the original layer group off as you don’t need it. What that will do is make the logo chrome.
If that is the effect you are going for in the end, then I would start by making the star solid instead of trying to make it empty space. To do the star in solid shapes, I’d suggest Primitive last column (far right) second row down in the following link. It just needs some skew to match the curve of the logo. Then fill the rest in with squares or other shapes etc. Also, when working in Create a vinyl group use as much of your screen as possible. The bigger you make it to start, the harder it is see minor imperfections once you size it down to fit on your car. It’s also easier to make sure your lines and curves are accurate when it’s bigger. There is a great tutorial at the top of this Paint Forum on creating logos that I have used, and it works. And there’s no shame in downloading an existing logo created by someone else and use it as a guide either to trace or just to put next to your own logo to look for differences.
https://forums.forza.net/turn10_postst104230_The-Vinyl-Editor---Shapes-of-Things.aspx
Also, something that took me awhile to catch on to that not everyone knows, the parenthesis shapes are awesome. The parenthesis in Lower Letters 5 and Lower Letters 9 and 11 are used in almost every vinyl group I make in some form or another. They are shown in the following thread if you scroll down to Lower Letters 5, 9 qnd/or 11
https://forums.forza.net/turn10_postst104232_The-Vinyl-Editor---Fonts-of-Knowledge.aspx
I hope this helps, if you need better, or more explanation let me know.
Best to make half the shape without masks, and then copy, and flip it.
