Set the player's inventory items count (items in item pouch and item box) to 9999.

Use it at your own risk.

Using dotnet:

$ dotnet build -c Release

Using Visual Studio:

1. Open MhwInventory.sln using Visual Studio
2. Debug -> Release
3. Build -> Build solution

$ MhwInventory <inventory base address>

1. In Cheat Engine, find the address for the count of any item box item
2. Right click address -> Browse this memory location
3. Right click memory cell -> Display Type -> 4 Byte decimal
4. Scroll up until you see 4294967295 4294967295 4294967295 4294967295 4294967295 4294967295
5. Scroll up more until you see the first 1123518944 1
6. Right click the first 1123518944 cell -> Add this address to the list
7. Copy the address and input it in program: dotnet run -c Release --project MhwInventory <address>

If the program breaks for some reason, validate the address offsets in InventoryHelper.MaxInventory(GameHandle handle, IntPtr address).