I’m trying to create a union of 2 parts.
Part 1 is a cylinder which I’ve already ‘unioned’ with a negative part so it has a hole in the middle
Part 2 is also a cylinder and that has a decal on it.
I’m now trying to union these 2 (cylinder) parts together (one smaller than the other) if I don’t include the decal they union fine, but I really want the decal.
When I include the decal I get the error message:
“Union failed - Selection contains CSG-incompatible instances”
I’ve tried changing the decal for a texture but still get the same error, I’ve tried png and jpg and tried adding transparency to the image, but still get the same error. I can’t find anywhere online that decals/textures are not supported in unions so I’m a bit stumped here, any suggestions greatly received please…
Thanks for reading…
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As far as I’m aware, only Roblox Studio parts are CSG Compatible. I’ve had this issue before, in which I just took out the decal, unioned the parts, and then put the decal back into the union. Of course, you may want to have the decal in a certain place on the union, which is a lot different.
If you have any images that would be great
Ah ok, all the parts are Roblox Studio parts. Yeah I really need the decal at a specific place here’s the parts before the union:

If I add the decal after a union it looks like this 
Yeah, because the decal is on one specific part, I don’t think it will look the same if you were to union the parts then put the decal on to it. Sadly, I don’t think there’s any way to union them and to keep it looking like the picture.
You could possibly export the union as a mesh and then put the decal/texture on to it, but I can’t help you there as I know nothing about that.
Good luck though 
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Ok cool as long as I’m not missing something stupid and obvious
just seemed like that should work to me…
Thanks for your time… maybe I’ll just have a go at a texture for the whole thing… 
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May I ask why you are not just welding the parts?
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To be honest I didn’t know that was an option. I’ll have a look into that thanks
I do intend to have a lot of these moving around so as long as welds don’t cause a degrade performance maybe that will be easier for me… thanks alot 
EDIT: Just added a weld, and that’s perfect! thank you @LuaBearyGood 