I designed this to fit my iPhone 12 Pro with a built in credit card holder on the back. I don't know if the dimensions for the 12 Pro and regular 12 are the same, so I don't know if it will fit a regular 12 or 12 Pro Max. If you try on something other than a 12 Pro, please leave a comment to let me know how it worked.

Dimensions (from digital calipers) of my 12 Pro I used when designing to help you decide if it fits another iPhone:
Length=146.8 mm
Width= 71.6 mm
Depth=7.9 mm

Camera Hole= 33.6 mmx31.1 mm

If you want to change colors, like in my pictures, then change:
--card holder at 13.7 mm
--logo at 17.1 mm
It should be the same for the Rebel and Imperial Cog, but I haven't printed the cog yet so I can't confirm, but it'll be close.

By the way, the points on the Rebel symbol are pretty sharp. I couldn't angle them so they weren't so sharp in the design, so I just use my nippers and cut them off at 30 degrees or so. Now they don't catch on my pocket or fingers.

The card holder holds 2 cards firmly. I have put three in, but it's pretty tight.

I included a thin layer in the design with a gap above and below so it doesn't stick to the top or bottom of the card holder. You can use pliers to pull it out after printing. You can put the insert back in if you only want to hold one card.

I used a lighter to melt the loose pieces on the inside after removing the support material, hence the black soot marks in the picture of the inside.

I upgraded my Ender 3 Pro with a direct drive extruder so I could print TPU. However, I did try printing this with PLA, and it seems to work. One corner did pull up from the bed, so it didn't fit perfectly, but I think it might still work. Also, I didn't print the card holder part, so I don't know how well it would hold cards with PLA. If you try PLA, please leave a comment to let me know how it worked.