Hi. I'm trying to gather specific items from a few mods, alter them and place them somewhere in-game that I can pick them up. I load the Oblivion.esm file and the mods that have the items I want into the TES Construction Kit with no active file since I'm not trying to alter any file. I duplicate the items I want by changing their ID's and when it prompts me asking if I want to change the ID or make a copy I choose copy. Then I change the copy's stats how I want them, place them somewhere I can grab them in-game, and save. But after I name the file what I want it to be saved as and click save, The TES Construction Kit crashes. Two different files with the name I saved as are placed in the save location but they have no file size, and there's 2 because they're different file types. I tried doing everything the same way with just the Oblivion.esm file loaded into the TES Construction Kit and it saves fine. But when I load a mod with it, it crashes.... what am I doing wrong? I'm just trying to make myself a nice set of armor and weapons with my own names and stats. Thanks.

You're doing several things wrong.

Firstly, you're in the wrong forum, The Construction Set forum is http://www.gamesas.com/index.php?/forum/24-construction-set-oblivion/.

Secondly, you have ESPs loaded into the CS as well as the one you have active for editing. A bug in the CS will guarantee a crash on save whenever you have other ESPs loaded in the CS, and the only way to avoid this crash is to make any edits in the Tamriel worldspace (doesn't matter what) - your active ESP must contain the Tamriel worldspace record or the CS cannot save.

Thirdly, you're trying to use one ESP to edit content from other ESPs. This is impossible the way you are doing this. You need to either install the Construction Set Extender by ShadeMe, or ESMify all the ESPs you loaded before your active ESP (and then ESPify them again before using them in-game). Wrye Bash is the best tool to ESMify ESPs, though TES4Edit can do it to. It would be much easier to just use the CSE instead however as it doesn't require ESMification.

If you're trying to create one ESP with content from various other ESPs but without needing those other ESPs, then you'll also need to use TES4Edit to ensure that all content required is copied across, then use the Clean Masters command to remove dependency from the other ESPs.