Besiege: How To Make A Trebuchet

Your base should look something like this, of course you can make adjustments however you want.

In case you were wondering how to make the main block float, just connect a few blocks from it and later delete them.

Make sure to add braces

Start adding blocks to the left and right sides in an L shape.

Of course it doesn’t have to look like this but this makes the machine very stable. Make sure to add braces

This is the tricky part I would say. Many people don’t know you can use the swivel joint to make things swing around if you manipulate the wooden blocks a bit.
Focus your camera in the middle of the the peak of the supports

Add 2 single wood blocks

Delete the block connecting the second block to the machine and leave it hanging in mid air.

Also delete the 2 blocks on the supports that are in line with the block that hangs in the air

Once deleted, add the swivel joints on both sides of the hanging block and re-place the deleted blocks on the supports.

Now that the hard part is done, start adding blocks until you have a lever of about 15×2 in size and don’t forget to add braces

Position your camera at the peak of the lever. Add a hinge and position 12 weights on top of it. Make sure the 6 weights that are hanging in mid air are facing the front of the machine and add braces of course

Position your camera at the tip of the base

Add a few wooden blocks but make sure the one going up is a single block, not a double.

Delete the extra blocks to leave the single block hanging in mid air

Add a holder and a bomb in it onto that floating block

Delete the holder and replace it with a grabber

This sticks the bomb onto the grabber, there is currently no other way of connecting the bomb to the grabber other than the holder/grabber swap

Now turn your camera around under the machine

Connect a contractible spring to the back of the floating block and the bottom of the front block of the lever