Craft your Dexcom Applicators into cool Speeders

If you use a Dexcom G6, you know how cool the applicator looks. Don’t throw that cool design away, mod it into a cool Speeder for your kids’ LEGO minifigs.

If you have some maker skills and a 3D printer, it's time to make some toys.

Two speeder designs and some different customization options are provided.

If you don’t know what a Dexcom G6 is, count yourself lucky as it means you don’t have diabetes.

Update March 2021: Completely revamped design for much easier cutting and 3D printing, plus a whole new "reverse cockpit" design.

Supplies

Dremmel rotary tool with a cutter bit that looks like a drill bit.
3D printer and models from https://www.thingiverse.com/thing:4166745
Cutting tools
- X-Acto knife
- Flat File
- Chisel
- (dremmel as already noted)
Superglue (aka CA) for some of the options. (I found Gorilla Glue gel-CA is very good.)
LEGO minifigure, a 2x2 plate, a 1x2 place, and a round 1x1 brick.
Optional
- Model airplane decals (or other stickers)
- Sugru putty, plumber's epoxy putty
- Drill or drill press
- Lego 4081 pieces (see photo). If you don't have some, they're cheap from lego.com.

Step 1: 3D Print Your Parts

Get the stl files from https://www.thingiverse.com/thing:4166745 and print them.

PLA is fine.
Standard quality is fine though for the top of the front blaster you may want a finer quality. If your slicer supports a dynamic layer height that would be ideal.
Supports are generally not necessary.
- The rear thruster/legs can print without supports but it does benefit from tree supports.
Some parts need to be rotated 45 degrees to lay flat. This will be very obvious.
The front blaster and headrest --both of which click into the button hole-- print in two pieces for easier printing and you glue them together once they are printed. The glue seem will be hidden in the final speeder.

Notes:

The cockpit looks good in many colours. I've tried white, gray, orange and red and all look good.
The cockpit is meant to make a very tight fit into the Dexcom so once you have printed it, you should file/sand the sides to clean off any slight protuberances that may hinder the perfect fit.
The rear jet is available as a single piece or as two, to make it look cooler with the warp turbines a different colour.
Any places where LEGO is to attach to the Speeder, I have designed places for an initial LEGO attachment piece to either press-fit in or glue in. I have intentionally not designed LEGO studs onto the 3D printed design; you just can't match the materials and tolerances of real LEGO with 3D printed PLA. You would be very disappointed when pieces no longer stuck after only twenty re-attachments.

Step 2: Open Up Your Dexcom

Open up your applicator and remove extra parts you don't need.

<5 minutes

Take your X-Acto knife and cut off the heads of the plastic rivets on the back.
- Place it vertically beside the rivets and then twist and pry and cut.
Pry open the Dexcom from the front with a flat-head screwdriver from the front or back.
Carefully remove the needle injector and dispose of it in your sharps container.
Use some pliers and pull out the flat metal piece.
Carefully depress the tabs on either side of the orange button until it releases. Don't press too tightly or they will get damaged and you want them so that you can re-insert the button later.
- Snip off the extra tiny rectangle on the bottom of the button. It will just get in the way later.
Pop out round metal spring and its plastic cover with a screwdriver. (The spring has already sprung and will not jump out at you or anything.)

Now you should be left with the white top, they grey bottom, and the orange button.

Step 3: Cut Out the Hole for the Cockpit.

Cut out the hole for the cockpit

20-30 minutes once you're good at it.

Looking at the white top piece from the inside, you want to cut out where I've shown with the orange lines. You'll be cutting right along the existing plastic.
Things to note
1. Marked in blue is where you will want to cut straight even though the plastic has a slight arc here.
2. In the front you'll be cutting two little corners. The corners start at the corner of the vertical pieces I've indicated in red.
I found that a small piece of 2x4 with a ~5cm trench in the middle of it was a good work surface to hold the rounded Dexcom body somewhat stable.
Make a first rough cut out with a dremmel to get the middle out. I've found that dremmels are very "jumpy" but if you get it a bit fixed in a piece of wood below the Dexcom you can kind of move the Dexcom around in a controlled fashion.
Make a second more precise cut around the outside.
Be very careful that you don't cut too far. Once you've cut too far, it's too late and you have to start all over again. (But that's not so bad because you have a million Dexcoms right?)
Make a third cut, removing some of the remaining vertical structures.
After this, it's time to use
1. A file or two
2. An x-acto knife
3. A chisel (especially good for filing down the vertical members)
Keep filing and cutting until you've perfectly cut right up to the existing plastic edges. If you can see faint "shadows" of where various structures used to be, you probably need to file/chisel/cut some more.
File from the inside out so that you can use the walls as guides. When cutting chiseling and filing always think about cutting parallel to the walls.
Try sliding the cockpit in from the inside. It should slide smoothly.
(If it doesn't slide smoothly, do some more filing.)
Once it slides in, hold the whole thing up to the light and see if there are any gaps. This should be a tight fit so if there are gaps it probably means you need to cut and file a little more.
Once you're done, you may want to take some #400 wet/dry sandpaper and do a final clean up on the sharp outside edges that you cut.

Step 4: Assemble Front-facing Cockpit (option 1)

The Front-Facing Cockpitrequires the fewest parts and is the obvious design. It has an aggressive nose built for Podracing.

Put a 2x2 LEGO plate in the cockpit (if you haven't already). It's a tight fit, you may need to use another piece of LEGO as a tool.
Fit the cockpit into the white top piece from the inside. Now from the outside, make sure the four corners are correctly positioned flush with the outside of the speeder.
Click the bottom on to the top. They should easily and firmly click together.
Add the orange button. To make the it look better, sand off the two bumpy attachment points where you had broken off the safety guard when inserting your sensor. (400 sandpaper or finer) Click it into place in the round hole in your speeder. Or, alternately, put the blaster in there if you made one. (See two steps ahead.)

General Assembly Note This applies to this and all other steps

I have designed these to require very little gluing; most things are a nice pressure fit. Where glue is required, I indicate it. If you would like to glue more things together where I have not indicated, while not strictly necessary, feel free to do so.

Step 5: Assemble the "Reverse Cockpit" (option 2)

The Rear-Facing Cockpitturns things sideways, with landing gear and a hyperspace-ready rear warp drive

Cockpit:

Put a 2x4 LEGO plate in the cockpit (if you haven't already). It's a tight fit, you may need to use another piece of LEGO as a tool. Fit the cockpit into the white top piece from the inside. Now from the outside, make sure the four corners are correctly positioned flush with the outside of the speeder. Click the bottom on to the top. They should easily and firmly click together.

Headrest:

Slide in the headrest in the round/rectangular button hole.

Rear Thruster and landing gear:

(Optional: add 2x1 LEGO plates to the bottom of the feet of the landing gear. Glue them in place. You have to decide now whether you want to do this because it affects where it gets glued. If you want these, work the LEGO in and out of the feet several times until they fit really well, and then glue.)

Hold the speeder level while you hold the landing gear up to the back of it. Look at it from the back and make sure everything is lined up and level. When you're comfortable about how this all lines up, superglue the two together; you can use a rubber band to clamp them together as the glue sets.

Step 6: Front Blaster (optional for the Front-facing Cockpit)

3D print your baster which comes in two pieces for easier 3D printing. Super-glue them together and clamp for a few minutes. You can align the pieces for gluing both with the aid of the edge profile or by inserting a paperclip in the small hole that's there for alignment purposes.

Add a 1x1 round brick into cannon barrel. It should be a nice tight fit. You can insert it in either direction depending on what orientation you plan for the LEGO pieces that will attach to it.

Push the front blaster down into the Dexcom and you're done.

Step 7: Add Your Own Creativity Here

Add model airplane decals that you can get from your local hobby store.

You can optionally add LEGO in a number of places. Experiment. (If you find that your LEGO no longer attaches to the 3D printed studs, you can always permanently glue a single real piece of LEGO on and then all subsequent pieces will work normally.)

You can glue studs to the back. (Photo above)

Optional: Add Holes for Side-weapons/thrusters. Using a drill press and your LEGO cutting jig, cut 8mm (5/16") holes in the sides of the dexcom.
Insert pieces as shown. Glue with Sugru or epoxy putty. LEGO part number is 4081. (They are quite cheap to order delivered from lego.com.) (I have ideas about 3D printing custom attachments for this step. But that's a future version of this project.)

Rather than adding side holes for lego 4081 as suggested earlier, try adding two Lego Technic pins, spaced 3 lego units apart so that you can snap on a LEGO Technic 1x brick with side-holes and attach a wing to that. (Having a 3 unit separation rather than 3 unit allows you to potentially have some pivot it you just want to use one of the pins.) See photo in the "thrusters" page.

(All photos here are from earlier prototypes.)

Step 8: Appendix: General Dremeling Notes

This is, in many ways, the most complicated step.

I have found that if I cut on top of a sacrificial piece of lumber and bury my cutting bit into that, I can move the dexcom against the cutting bit in a fairly controlled manner. Otherwise, I find the dremmel very "jumpy" and hard to control.
The best bit I found was a Dremmel rotary tool with a cutter bit that looks like a drill bit.
Rotary tools seem to have a mind of their own and will zip off and accidentally mar your work. Keep this in mind and go in a direction so that it is less likely to zip off and if it does, it will only mar the inside, or something unimportant, not some exterior bit.

Obligatory safety notes.

Be CAREFUL. Rotary tools have a mind of their own. Keep your fingers out of the way because the tool will zip out of your control occasionally. Ensure that when this happens, it is not possible that your fingers are in its path.
Do not let your kids use the dremmel.
Follow manufacturer's safety procedures and use eye protection.

Step 9: Give Me Feedback

After you've built your speeders, let me know how it goes, let me know if you have suggestions. I'm especially interested in ideas that add "play value". (I'm very concerned that this is super-cool from parents' point of view but kids will say "meh".)

Ideas for feedback information:

Ideas for modifications to existing 3D parts that add more play value. Ideas from your kids, not from you. :0)
Ideas for new 3D parts. e.g. Thruster/blaster LEGO attachment points that can be added anywhere on the side or back. A hinged cockpit upper cage and steering wheel assembly.
Something to attach to the bottom.

email me: dexcom.speeders (at) gmail (etc)