need help fixing my atx case

[dreamcast4599]

so picked up and early to mid 2000's atx case for 10$. to use with my core i7 4790 gaming setup im building. it looks like the previous owner filed down one of the side panels with a dremmel or sand paper, no idea why they did that tho. im going to assume maybe they had trouble getting the panel to close properly. anyhow what are my options as far as filling the top of the panel to make it level with the top of the case below are some pics i took to best illustrate the issue im thinking maybe some kind of putty to fill in the gaps so that when i close the side panel it doesnt look like theres a huge gap between the top of the case and the side panel when you close the side panel the gap is very noticeable electrical tap was placed simply to show where it was sanded

 

what are my options  quick edit i should add that i added some glue to the side panel where the seam was coming apart

Edited February 27 by dreamcast4599
added more context to my post

[thrasher_565]

i mean i guess there probly some metal body fillter that you might be able to build it up then sand it down. but i mean its a $10 case thats been used...

 

some case had sidepanals the just sucked.

[dreamcast4599]

@thrasher_565 i got it sorted im gonna use some thin metal sheets to cover the gap will make a new post when the build is 100% finished along with pics