This isn't a guide for where to find every single golden spatula since there is plenty of those already online, this is just a method I found to help you grind shiny objects for Mr. Krabs' spatulas since that is likely the last thing you will have left after beating the game. At a rate of 2200 shiny objects per minute this method takes roughly 50 minutes starting from scratch to get all 108,000 shiny objects you will need, a bit faster than other methods I've seen posted around.
To get to the spot quickly you can fast travel directly to Mrs. Puff in Jellyfish Fields, then progress a little bit forward in the mission until you get to the wall of stone tikis. Go just beyond this wall to the clam to trigger a checkpoint, then every time you respawn run at the stone wall, destroy it by hitting the lightning tiki, then just jump into the nearby waterfall to respawn back at the clam with the wall respawned as well. You can get this cycle down to about 15 seconds per run (including load times) for 530 shiny objects per run.
EDIT: This solution is very dependent on load times, I used a One X with external SSD so if youre getting slammed with long load times an alternative may be to go down the guppy hill in the sand mountain level, destroying as many tikis throughout the run as you can.
(Thanks to BDTerry for this) if you've collected all of the spatulas but are at 99/100, check to see if the spatula in the dining room of the Chum Bucket respawned, apparently this is a common thing. If that isn't the one you are missing try to go around looking for spatulas that may have 'respawned'.