Introduction: The Ultimate Self-adjusting Door Opener 9000 - 3D Printed

About: I'm a 17 year old Fusion 360 and Tinkercad user. I am currently working on a big format CoreXY 3D printer.

I am a (15 year old) 9th grade student of Arizona College Prep Erie Campus, and this is the 3D printed (potentially overkill) Ultimate Self-adjusting (non-contact) Door Opener.


This is a door opener for using door handles without actually touching them (I jokingly call it the Door Opener 9000). This one is specially designed so that it can self-adjust to many door handle sizes, making it versatile and easy-to-use. Also, the user cannot easily touch the contact surface when gripping the door opener properly, making accidental contamination by touching unlikely.

Edit: I originally messed up the wording for "door handles" and referred to them all as "doorknobs". This device only works for the lever type door handles, not the round knobs!

How does it work?

The Ultimate Self-adjusting Door Opener 9000 has a total of four parts, being the two grips/clamps and a plastic bolt and nut assembly. Only the grips are important as the bolt and nut are only used as a hinge. The two grips will clamp onto the door handle while you push down and rotate. These grips are meant to have a flexible strand of string/filament in between them so that the self-adjusting action can work flawlessly. However, the mechanism can still be manually controlled without the flexible string/filament.


This tool is mostly 3D printed. None of the 3D printed parts require support as long as you print them in the correct orientation.

Here is the list of supplies you will need to make this thing:

  • Well-tuned 3D printer
  • Opaque rigid filament
  • One small strand of flexible string/filament (optional)
  • Super glue or fast-setting epoxy (optional)

As for print settings, these are what I recommend:

  • Any appropriate layer height (I used 0.2mm)
  • Any appropriate nozzle diameter (I used 0.4mm)
  • 10% or less rectilinear infill (to save on filament)

Step 1: Design Overview - the "Purple" Grip

The design overview is a part of the instructable that shows how I designed the door opener. It is not meant to be recreated exactly one-to-one, but it gives the reader a basic understanding of how I went through the workflow to design such tool.

You may skip the design process steps if you are not interested in looking at how I designed this.

This is the purple grip. It is one of the two grip parts, and this one has a handle on top.

Step 2: Design Process - Purple Grip - Body

I started off with a sketch consisting of mainly circles and slots and extruded by 80mm.

Then I used the same sketch to cut out a hole for the handle.

As easy as that, the purple grip is done (for now).

Step 3: Design Overview - the "Blue" Grip

This is the blue grip. It is the grip part that actually rotates.

The steps I used to design this can be optimized, but it works.

Step 4: Design Process - Blue Grip - First Sketch

I made a sketch with a circle that is centered with the hole in the purple grip and touches the outer edges (like shown in picture).

Then I extruded by 5mm as a new body. This is the start of the blue grip.

Step 5: Design Process - Blue Grip - Second Sketch

Make a second sketch like this. This will give the grip its shape.

Then extrude it by 5mm while keeping the purple body hidden. Make sure the operation is on "join".

Step 6: Design Process - Blue Grip - Third Sketch

Create a sketch like shown in the first picture. And for the next three sub-steps, keep the purple body hidden.

Then I performed three extrusions:

  1. Extrude the part of the sketch shown in the picture (the narrower grip part) by 80.2mm
  2. Extrude the entire face using the "two sides" option, one side is 80.2mm and the other is 85.2mm. This will create an exact offset on the other side of the part.

Step 7: Design Process - Blue Grip - Hinge Cutout

Re-enable either sketch 1 or 2 and extrude the 9mm hole in both directions on the "cut" operation.

Step 8: Design Process - Blue Grip - Thumb Rest

If you were to make this, this step is optional, but I added a thumb rest to the part so that you can control the rotation with your thumb.

This is done by drawing a 15mm diameter circle on one side of the blue grip and extruding it down by 3mm.

I then repeated the same step for the other side.

Step 9: Design Process - Fillets and Chamfers

Add fillets and chamfers to the parts. This is not only for aesthetics, but also for the door handle to slip in easier.

The most important places to add chamfers are: the bottom (inner edge) of the grips and outer edges of the thumb rest.

All the fillets and chamfers are highlighted in the picture.

And that's the grip parts done!

Step 10: Design Overview - Bolt

This is the bolt. The bolt and nut act like a hinge for the grips.

The following two steps will describe the design of the bolt.

Step 11: Design Process - Bolt - Body

Make two circles, one being 9mm, and the other being 15mm. The 9mm circle while be the bolt shaft while the 13mm circle will be the bolt head.

Extrude like shown. The first extrude (on the bigger circle or bolt head) is by 5mm and should be on "new body" operation. The second extrude (on the smaller circle or bolt shaft) should be 96.2mm like shown in the picture.

Step 12: Design Process - Bolt - Thread

Using the super convenient thread tool (found in the "create" menu), make a thread that follows the parameters shown in the picture. It should only have a length of around 7mm.

And that's the bolt done.

Step 13: Design Overview - Nut

This is the nut, which is going to be mounted on the bolt to keep the hinge in place. It is not meant to be screwed on tight as that would limit the motion of the grips.

The following two steps will describe the design of the nut.

Step 14: Design Process - Nut - Body

The same sketch as the bolt, 9mm and 15mm circles, can be made for the nut, with the only difference being that it's located on the other side.

Then extrude 6mm like shown. Keep the other bodies hidden while you do this.

Step 15: Design Process - Nut - Thread

Create a thread in the inner walls of the nut using the same thread tool that's found in the "create" menu. Keep in mind that the thread should be of the same thread profile as the bolt.

And that's the nut done!

Step 16: Design Process - Thread - Clearance

Some printers really don't like to print threads, so I often offset them a little using the push pull tool. The amount of offset depends on your printer. I usually do -0.1mm for both the thread profile and the outer diameter.

Step 17: Design Process - Finishing Touches

These are just some finishing touches. I added extra chamfers to some parts and insert holes on the sides of the grips for easier gluing of the piece of flexible string/filament.

And that's everything in the design process!

Step 18: Overview - Design Files

Attached are the .step and .f3d design files. You are free to edit and redistribute them in any noncommercial manner.

Step 19: Assembly - 3D Print

3D print the following parts in orientations shown in the picture. No supports are required.

  • 1x Purple grip
  • 1x Blue grip
  • 1x Bolt
  • 1x Nut

Step 20: Assembly - Animation

Follow this animation to assemble this tool.

Here is a breakdown of the steps:

  • Put the purple grip in between the two outer plates of the blue grip
  • Align the holes that are present on both the grips
  • Insert the bolt into the hole
  • Screw the printed nut into the bolt to lock it in place. Finger tight or even loose is enough as the nut is only to keep the bolt from falling out.

Step 21: Assembly - Flexible Piece

Get a piece of flexible string or flexible filament. I used 82A Filaflex, but Ninjaflex or even 95A TPU would work as well.

Fill the premade holes with super glue or fast setting epoxy, and then insert the flexible piece. Let it set for a period of time depending on which glue you use.

Don't use regular glue as they are often not strong enough. Unless you're talking about flex glue of course, they are overqualified for the job ;) (just kidding).

There should be just enough tension that the grips want to stay closed, but not so much that the grips would not easily open.

Step 22: How It Works

How do you make sure make sure it doesn't slip on the door handle?

The two grips basically clamp onto the handle to keep the tool from slipping. The flexible material between the two grips ensure that clamping force is always applied.

How does is this tool self-adjusting?

The flexible material in between the two grips allow for use with door handles of different sizes as it will always maintain a clamping force.

Step 23: The Door Opener in Action

These gifs are of the door opener being used to open/close doors.

As you can see, they're quite easy to use and work for different door handle sizes (except for round doorknobs since those need to be rotated).

Step 24: Conclusion

And that's it! I hope you liked my instructable and maybe print one of your own to use at home.

In any case, I hope you have a wonderful day! :)

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