Some parts of my modal appear one way.
How does this happen and why?
turn off the transparency on the creation
I don’t think i ever turned on such a setting
I’m not sure how you created this gun, but I’m guessing it was via Blender.
Roblox culls backfaces. Turn Blender’s culling on as well when modeling to see what’s being culled out and reverse the face normal.
To do so, press the N key when in Blender, go under the Shading submenu, and check the Backface Culling box.
Yes the modal was made via blender
sometimes it turns on by itself based on the structure
Check the backface culling box when modeling and then click the Flip Direction button on the face that’s being culled.
You can find an in-depth tutorial on how face normals work by looking it up, either via the Blender forums or just on YouTube.
It does appear to be an older version. You can get an up-to-date version on Blender’s website for free, or you can get it on Steam and get updates whenever they release. The most recent version is 2.8, but I use 2.7.
If by chance you still have your asset saved in file, go back into blender, go to the Viewport Overlays setting, (as in the picture below i’ve circled the button)
Then you should look for a box that says “Face Orientation” once you click that, your mesh should turn blue, if its fully blue that means your mesh has normals facing the right way, if you see any red Spots all you have to do is select it (In Edit mode) and press Shift + N, if it still didn’t turn blue make sure to check/uncheck the box like below until the face turns blue.

Good luck!