This is small plugin that replaces decoy model with snowball model. Models may not seem to work very perfect, because they are from garrysmod
Config file: cfg/sourcemod/snowball.cfg
sm_EnableSnowballTrail
sm_GiveAnotherSnowballAfterThrow
sm_SnowballHitDamage
sm_SnowballHitPlayerType
sm_SpawnSnowballOnPlayerSpawn
sm_TimeToGiveSnowballAfterThrow
sm_SnowballEnable
sm_SnowballUnfreezeTime
sm_SnowballEnableOnlyWarmup
Explantion for each cvar in the config file!
I have also added one event for developers, if they want to do something with the guy who hit someone or who was hitted: Snowball_HitPlayer(int client, int attacker).
Download & put files from sendproxy
Download snowball files & put them in server
Restart server
Configure convars in cfg/sourcemod/snowball.cfg
Lord Cheaterfield: some ideas and helping to test this. No idea: for making this snowball model in garrysmod.