Can anyone help me with making a paint tool with certain assets?

You might already go ahead and tell me that there's already countless free models that can do this but it's about a paint tool that has a paint brush size script at it's hand at the maximum of 5 with the way of increase being through hotkeys such as q for decrease and e for increase, but the paint tool is also able to have the blocks be seen by the other players and be able to be held down to paint as well with a feature of not being able to paint blocks that are locked if it's possible, it doesn't matter, I just need help with making a paint tool that can increase the size of the amount of blocks being painted and the hotkeys for the player being q and e for increase and decrease and when the player paints a block, it would also be registered on other player's games. You will probably ask what have I done so far, I so far suck at scripting and have no idea on how to get this done, please help me, I have been dealing with the issue of making a paint tool like this for months with no success.