Gmod Advanced Inventory System: https://originahl-scripts.com/gmod-scripts/3939/gmod-advanced-inventory-system

Contents : 
0:00 | Introduction of Gmod Advanced Inventory System
0:04 | Default inventory style
0:09 | Customization demonstration 1 of 3 (Starwars)
0:36 | Customization demonstration 2 of 3 (Anime Style)
1:06 | Customization demonstration 3 of 3 (Medieval Style)

Users Features :
1:31 | Take the items you pick up in your inventory. This will be saved.
1:44 | Give a description to an object, a tip on how to use it or a story. 
1:54 | Control the numbers of items you want drop 
2:08 | Don't drop 10 items but stack them together on a single entity to optimize the server for this kind of interaction. 
2:32 | Equipment switch shortcut bind system (can be disabled) 
3:05 | Check the ammos you hold from your inventory
3:31 | An inventory upgrade system that you can implement. The player spawns with a minimum set in the settings.
4:03 | A swep that are simply the hands. With pick up and move the objects. Left click to pick up and right click to drop where.
4:16 | Unequip weapons to store them in the inventory.
4:38 | Use the items from the inventory
4:56 | Administration panel for management

Gmod Advanced Inventory System is designed to run as a standalone system, meaning that no gamemode is required to run it. A variety of options will allow you to adapt the style of the inventory to your gamemode on your garry's mod server. You will be able to offer upgrades to the maximum capacity of the inventory depending on the level of the user, or in the form of spawnable entities. You can also create a whitelist of items to secure your server. A customisation system unlike anything you've ever seen on Garry's Mod will allow you to easily blend it into your server's style without coding a single line in Lua, see the videos or screenshots. Create the inventory you imagine it will be unique. The idea is that you have a unique inventory so that your server doesn't look like any other. You can change the style of your inventory overnight for events such as Halloween or Christmas without having to buy another one. Gmod Advanced Inventory System is designed to be an alternative to ItemStore without imitating it or DarkRP Pocket.