1. How to Hollow out a box in Tinker Cad
Mark Weaver

2. There are a lot of shapes that Tinker Cad provides to make things out of, but none of these allow you the opportunity to experiment with the inner workings of the piece until edited.

3. To start you will pull a square onto the surface, and for the purpose of hollowing precisely, you should drag the ruler to the work plane as well, so that you can type in your measurements.

4. After dragging the ruler to your surface, measurements will become visible of your square.

5. Having this 20x20x20 cube, make a duplicate.
(control+c, then control+v)
This will provide you with an identical object to edit and group to your original shape.

6. Because we want it to fit snugly inside the pre-existing piece, I have found that the second object needs to be two numbers lower in each direction from the original dimensions. Thus, I start by changing the length from 20 to 18.

7. I then alter the height accordingly.

8. Before I change the width, I change the shape to a hole (the striped gray circle in the corner of the shape bar)
A hole is a part of your object that will be negated from the final object once grouped.

9. First I line up the cube hole length-wise
First I line up the cube hole length-wise. The reason I have found that 2 is the best increment downward is because the mathematics of keeping 1 space on either side is much easier. Also, the arrows on your keyboard shift over 1 space every time they are touched, so this makes adjustment very simple.

10. Next, with the red arrow the ruler creates above your object (or what I have been calling the Christmas tree), I lift the object up one space.

11. By starting like this you can check either side to make sure that the object is equally balanced. The back side view matched up perfectly with the front!

12. From this point, I go back to looking at the object from the front
From this point, I go back to looking at the object from the front. Using the projected ruler numbers again, I change the width of the hollow cube to 18. (A Step I bet you have been waiting for for quite some time)

13. The tools are very helpful in that they highlight when you want to edit to make sure you are selecting the right one.

14. After this change is made, the object shrinks forward, and it becomes as easy as hitting the arrow key back 1 time to get the hollow part dead center to the original cube!

15. Next, and perhaps the most important thing to do, is to highlight over the entire surface and group the different cubes. This will subtract the space that the hollow cube and then the object can be moved in its entirety instead of having to move both to the same spot separately.

16. You can’t see the alteration we made inside because of the solid exterior, but I wanted to show you guys how to remove one side of the box in order to see it. To do this, I drag a cube onto the work plane with the same 20x20x20 dimensions.

17. I then turn it into a hollow shape, and I decrease its height to 1
I then turn it into a hollow shape, and I decrease its height to 1. You may be thinking, why 1 instead of the normal 2? Well, seeing as we are taking one side of a surface off, we don’t need to account for both sides it will leave (2), we are simply removing one.

18. With the same methods that you used to position the hollow cube inside, place it on top of the cube, lining directly with the top measurement (thus placing it 19 from the work plane).

19. When all is said and done, and you group these objects together, the work you put forth is evident. The box that you have created is PERFECTLY even on all side and the options for what you can do inside of it in the future is limitless.
Guess it doesn’t hurt to think inside of the box after all? Does it?