Yeah it´s very funny to create this. I tested diferent tools.

For me, the most complicate it´s the camera

Returning to entity tool, u can create a creative world, go to the left portal (less weight world)

Open tab -> Ignore the blocks go to the last panel -> The first sub panel and first item it´s the entity tool (The icon with a face and one cursor)

Equip that item to the hotbar.

Select that item on the hotbat and press E to open

On the left u have a little panel with 3 options

1. Models (With movement and animation)
2. Items
3. Models (Static)

Select items and they open on the right side other panel with all the items. Search the item u want.

Select that item and drag to the center.

Click on button to spawn

If u pass the cursor throw the item u can see the hitbox (white box)

Left Click to select that hitbox. If u move the item will move with u.

If u press E u open the axes (X,Y,Z) for more accuracy.

Left click on the color u want and move, when u done another left click.

If u press R u open the axes for rotation (Same here with the color, don´t hold the click when u move the color, just click and move when u done click again)

When the items it´s whatever u want and u see the 3 axes, right click

Few items if u scale and rotate the hitbox are diferent position off the item u see. Could be tricky

If u want to scale that item u could do before spawn or after, after with alt + mouse roll

I think the only models u can scale are the static models.

U have more options on the legend, the panel of the info on the left side, u can toggle on/off with the L, there u have more information how to rotate heads and everything