Tools...
Axes...
Axe: Occasionally available in the tools section of Nook's shop (after upgrade to Nook 'n' Go) for 500 bells.
Silver axe:Occasionally given by Serena, summoned once per day by throwing a basic axe into the town fountain.
Golden axe:Occasionally given by Serena.
Nets....
Net: Usually available in the tools section of Nook's shop (all incarnations) for 500 bells.
Silver net: Rarely available in the tools section of Nook's shop (after upgrade to Nook 'n' Go) for 500 bells.
Shovels....
Shovel: Occasionally available in the tools section of Nook's shop (all incarnations) for 500 bells.
Silver shovel: Given by Resetti the first time a character enters the Surveillance Center.
Golden shovel: Buried shovels turn into golden shovels the next morning at 6 am.
Fishing Rods....
Fishing rod: Usually available in the tools section of Nook's shop (all incarnations) for 500 bells.
Silver rod: Rarely available in the tools section of Nook's shop (after upgrade to Nook 'n' Go) for 500 bells.
Watering Cans....
Watering can: Occasionally available in the tools section of Nook's shop (all incarnations) for 500 bells.
Silver can: Mail from "Posy Farm" after buying 50 bags of flower seeds at Nook's shop.
Golden can: Awarded by the Town Hall after maintaining the best environmental status for 15 consecutive days.
Slingshots....
Slingshot: Occasionally available in the tools section of Nook's shop (after upgrade to Nook 'n' Go) for 500 bells.
Silver slingshot: Rarely available in the tools section of Nook's shop (after upgrade to Nook 'n' Go) for 500 bells.
Golden slingshot: Appears as a "three-balloon" balloon after shooting down at least eight balloons.
Timer....
Timer: Occasionally available in the tools section of Nook's shop (after upgrade to Nook 'n' Go) for 500 bells.