Yes, there are many mods that can add new tools, but they end up being huge.

I think minecraft should have a new tool for transporting water or lava. This tool would have be carried like a sword, so you can see it in your hands, but if you let go or change items, you drop it. To make this tool, it would be like this.

B=Bucket
S=Stick
T=String
L=Leather
BSB
TLT
This transporter could carry 4 times as much as a bucket.

Also, i think there should be some type of backpack that coes in place of a chestplate, that can carry as much as a small chest. For this you right click on it while it is in your inv. to open it and fill it like a normal chest. then you press esc. to go back to your inv. you cannot fill it unless it is on your back.
To craft it, it eould look something like this

C=Chest
T=String
S=Stick
SS
TTC

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