Part 1: Initial table setup - https://www.dailymotion.com/video/x7tzm81
Part 2: Making 8 tables - here
Part 3: Final tables - https://www.dailymotion.com/video/x7u270h
Now that you have one bug table, you can use it to quickly make many more tables. Note that bug cages overlapping the east wall when you leave the room will be deleted, part 3 will cover how to make special tables to handle that. Even if you don't make those tables, using these is still much faster than any other method out there.
Credit goes to the HotGF crew for providing helpful info and discovering the original 2x1 and 1x1 methods: Crud, Chen, jzt, hhccyy, Code-EV, and SawyerG.
Q: I can't get two sharks/bug cages to appear.
A: The sharks and bug cages can hang off the table to the east and south, not to the north and west. If you decided to do your table with sharks and cages hanging off a different way than in part 1, refer to part 4 above. If you try to hang an item off the wrong edge, it will create an invisible item instead which will interfere with your tables (see below or watch the video on fixing issues).
Q: What can I use besides crowns? Can I use NMTs/gold nuggets/clothes/pagodas?
A: You can use any 1x1 item that can be placed on a table and is solid. That means no NMTs, gold nuggets, or other resources. The only clothing that can be used are headwear, accessories, and shoes.
Q: How do I used something other than crowns?
A: Remove the sunken crown, then place another item in its place.
Q: What do I do if I don't have a shark model or katana?
A: Lots of people are selling or giving away those too, but you can also use the 50" LCD TV or lab-experiments set which you sometimes find in the Nook shop.
Q: Help there are invisible items in my room/I can't place items on an empty table.
A: Move your bug tables away, place empty tables in the suspected areas, leave the room and come back. The invisible items should reappear.
Q: Will this corrupt my save file if I leave the tables like this?
A: No. You can save your game with the tables set up and they'll be there when you play again.