Being able to 3D print a water bottle would be super cool, so I'm going to show you how to create the model!
I'm going to show you how to make a 3D printable water bottle using Autodesk 123d Design desktop version! It's awesome, download it here http://www.123dapp.com/design
After thinking through several water bottle designs, I concluded that doing it this way is one way to make it 3d printable without having a screw on top. The two plugs on the top block two holes: One for drinking from, and another larger one to make cleaning the bottle more convenient. Due to the small decrease in the size of the plugs in relation to the holes, being a fraction of a millimeter smaller, the plugs should fit snuggly.
I attached an stl. file with the design. It's in separate pieces in the model, so that you can print it then put it together
First, download 123d Design, start a new project, and change your units to centimeters
Step 1: The Body
To make the body:
1) Create a cylinder from the primitive shapes that has a radius of 3.5 cm and a height of 20 cm
2) Use the shell tool to hollow out the cylinder by selecting both the top and bottom bases with the Ctrl key. Make the thickness 0.5 cm
3) Create another cylinder with the same radius of 3.5 cm and a height of 0.5 cm
4) Tap the bottom of the smaller cylinder to the top of the larger cylinder
5) Create another cylinder with the same radius of 3.5 cm and a height of 1 cm
6) Move the large cylinder up 1 cm
7) Tap the top of the new smaller cylinder to the underside of the larger cylinder
8) Use the combine tool to combine all of these tapped objects into one object: the body
Step 2: The Top
To prepare the top of the bottle:
1) Create a circle on top of the body at least a cm in, with a radius of 0.75 cm
2) Extrude the circle down 0.5 cm so it goes through the top of the body
3) Delete the remaining circle that's above the hole
4) Create a cylinder with a radius of 1 cm and a height of 3 cm
5) Use the shell tool to hollow out the cylinder by selecting the top on bottom bases with the Ctrl key. Make the thickness 0.25 cm
6) Move the small cylinder up 21.5 cm
7) Align the small cylinder so it's over the hole accurately, like shown in the pictures
8) Create an ellipse on top of the body, with a major axis of 1 cm and a minor axis of 2 cm
9) Like the other circle, extrude the ellipse down 0.5 cm and delete the remaining ellipse
10) Combine the two pieces into one object
Step 3: The Plugs
To make the first plug:
1) Make a cylinder with a radius of 0.745 cm and a height of 4 cm
2) Center another cylinder on top of the last one, with a radius of 1.5 cm and a height of 0.25 cm
3) Create a torus with a major radius of 1.5 cm and a minor radius of 0.15 cm
4) Rotate the torus 90° and position it on top of the plug, like shown in the picture
5) Isolate and select the torus, press Ctrl+c, then Ctrl+v, and move the copied and pasted torus off to the side
To make the second plug:
1) Create an ellipse with a major axis of 0.98 cm and a minor axis of 1.98 cm
2) Extrude the ellipse up 2 cm
3) Create another ellipse centered on top of the last ellipse, with a major axis of 1.2 cm and a minor axis of 2.2 cm
*You can also delete the unnecessary ellipse that you used to make this ellipse
4) Extrude the ellipse up -0.25 cm
5) Position the copied and pasted torus onto this second peg like the last one.
6) Combine the parts of each peg with the other parts of that same peg, so that each peg is one whole object
Step 4: Finishing Touches
All that's left to do now is round the edges of the objects and change the materials.
Use the fillet tool to round the edges you want. Click on the body of the water bottle and make the material "glossy plastic", and the color you want. Make sure to check the box "apply overlay". Then, click a plug and make the material rubber, choose a color, and select the other plug with the materials window still open. This makes the other peg the same material and color as the one you're working with. After this you're done!
Thanks for reading! If you enjoyed this, then a vote in the 123d Design Contest would be great, thanks! :) You can check out my other other instructable for a 3D printable No Wobble Cup Coaster at https://www.instructables.com/id/3D-Printable-No-Tip-Cup-Coaster/
Comment if you have any questions!
Also be sure to check out some other things you can make with 123d Design at https://www.instructables.com/contest/123ddesignchallenge/ and https://www.instructables.com/group/123d/