So in order to create this marble maze of yours, this is what you'll need in terms of materials in order to create this:
1. 1 bottle of wood glue
2. 12 1-inch wood screws
3. 3 1/6th of an inch thick boards
4. 5 1/4-inch thick square dowels
5. 5 1-inch thick boards
6. 3 1/8-inch wooden dowels
7. 1 marble
Now in terms of tools, this is what you'll need in handy:
1. A drill (or drill press)
2. drill bit (in order to put in the wood screws)
3. 11/16 spade drill bit (I'll explain that one later on)
4. a saw of some kind (scroll saw I preferred)
5. A file (in case you want to have smooth edges for it then)
Once you have gotten those materials we are ready for the next step. (proceed to step two.)

Step 1: Measurements of the Materials

Here are the measurements that you'll need in order to create your maze:
Wooden board #1 (2): 11 1/2 inches long and 3 inches tall.
Wooden boards # 2 (2): 13 inches long and 3 inches tall
Short dowels (2) : 4 1/2 inches
Long dowel : 15 inches
Base wood plate 13x12 1/2 inches
Inner/ exit part of the maze plate 11 1/2x11 3/4
Maze plate 11x11 1/4
Square dowels: 1: 4 3/4 inch
2: 2 3/4 inch long 1/8 inch thick
4 pole holes 1 7/8 tall holes
Handle 5/6 of an inch

Step 2: Making the Bottom of the Structure

This is where everything is going to go into, so be prepared with you measurements:
This is where your going to need your drill and saw. With the spade drill bit, drill at the bottom opposite ends at the front facing wood, and have it have a decline to it in order to create a way for it to easily come out later on.

Now for the ?? Wooden dowels we need to have ? Inch tall incision in the center of each of the four boards, which is ?? Inches for the center. So after you mark that spot, you'll need to drill with a ?? Inch drill piece. Then with the saw of your choice, you saw it to length until you've reached the measurements and then carve it out until your dowel is able to fit.

put the ??inch boards parallel to each other, then do the same to the other 2 boards you have and make it into a square, then with you drill, use the drill bit in order to put the wood screws in ( make smaller holes with a drill bit so as to have an easier time putting the screws in) .put two screws on each corner as to keep it together.

Now for the bottom part of this, you would use the ?? Inch thick piece of wood and make sure your measurements are correct, the with the help of your drill and its drill bit, you can now put the last four (or more) screws to connect the bottom to the 4 boards themselves.

Voila, you completed step 3!!!

Step 3: Inside the Structure

Here's where you want to start, with your 1 foot 5/8 Inch wood plate you can first glue on your 1/2 inch thick wooden dowel onto the bottom top right of that plate ( I suggest taller so the ball will roll better the to the exits) then with your 2 3/4 inch Tall, 5 1/2 inches long, diagonally cut piece of wood and put it on the right outer edge of the inner plate and goes 5 1/2 Inches from the bottom of it, so as to keep the ball rolling in the right direction, then you cut three square wooden dowels into 1 that's 5 Inch long, 2 that are 2 3/4 Inches (both are 1/8 of an inch thick), as to also keep the ball on task towards their respective holes. Then you've finished doing that, you may glue on the 1/2 inch thick wood dowel and the rest of its base onto the finished product of your bottom structure. And if you did not put the exits in. Correctly, like I sadly did then the solution was simple ,make a diagonally shaped part of the wooden board out of a extra board and make it so your able to make the ball automatically go to the exit.

Step 4: The Maze Its Self

This part of the project is what your imagination wants to be (or whatever you can fit on that ?? Inch plate of wood), you COULD copy my idea of the maze, but that can't stop you from making your own! But since some people will choose either way, I'm also putting down all the measurements of the walls (1/8 of an Inch thick square wooden dowels)

1. 7 1 inch
2. 1, 2 1/4 inch
3. 1, 1 3/4 inch
4. 2, 2 1/8 inch
5. 2, 2 1/2 inch
6. 1, 7 1/2 inch
7. 1, 2 inch
8. 2, 3 1/2 inch
9. 2, 1 1/2 inch
10. 1, 3 3/4 inch
11. 1, 1 1/4 inch
12. 1, 5 1/2 inch

For the marble, you will need to have the hole be able to fall through it with ease, so with you trusty drill and 11/16 spade bit, you can drill the right holes where ever you would like on there.

Step 5: Finished Product

Now that you completed all the other 5 steps, YOU HAVE A MARBLE MAZE (go get yourself a cookie, come, on you deserve it) now after testing to see if it's actually possible to beat, challenge your friends to see who can beat it the fastest, or if it's hard enough, beat it. Other than that, enjoy you amazing new toy.