Depends. I have had mixed results using my custom sounds and moving the models around the players for weapons and projectile types. You will likely need to use a couple tools to do something like this. One being a system to push down the files to the end users I use mani-mod and its downloads.txt to send the files down. Then you will need to modify the class files for each class and change out the models and most of that can likely be found in the /tf/scripts directory or via server side cvars.
Most of this will not be stuff you can do at the map level. If you got a custom skin and model you want to try out send me a link and I can test it on one of my hosts for shits n giggles.
It might be possible, but don't expect players to like it. Forcing custom skins and models on people is not at all friendly, and might even get players into trouble with VAC unsuspectingly.
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