Household hacks with a 3D printer

I’m often asked “what is a 3D printer good for, isn’t it just a novelty”?  So here are some examples of household hacks, in no particular order.  I’ve chosen examples that satisfy two criteria.  First, it didn’t take me more than an hour to whip up the CAD model (and, in many cases, it took just 10-15 minutes), so it qualifies as a “quick hack”.  Second, it’s of general household use, so mechanical assemblies, 3D printer parts, etc, were left out.  Some of these are published on Thingiverse (linked from the post headings).

Eyeglass frame fix

This is one of my favorites.  It was one of the quickest to make, but it was used a lot.  My mother has her favorite eyeglasses and is loath to change them.  However, over time, the arm loosened and they would constantly slide down her nose. Tightening the screws didn’t do anything anymore. So, I quickly designed a clip that slides over the frame, and has a tapered nub to apply pressure to the arm (printed in ABS, so it has some flexibility).  Guess you could call it an “eyeglass arm pretensioner attachment”.  She’s been using them for years, and asked for a pack, in case she looses one (printing a set of six takes about 15 minutes; the example in the photo is an early print in black, instead of brown).


 IKEA cheese plate fix

Moving on to something I was loath to change: an IKEA cheese plate, which IKEA has long since stopped selling in the US (I guess cheese isn’t such a daily staple here, so it probably didn’t sell well).  In fact, I did try to find a replacement, but failed.  Unfortunately, one of the times it was dropped, one of the handles broke.  Since it’s made out of polypropylene, it was impossible to glue.  So, here’s what I did: I traced the outline of the handle with a pen on paper, then scanned it, and then digitally traced it using InkScape, and inset the inner long edge (so the cover could fit nicely; see photo inset).  Saved as DXF, imported into OpenSCAD, and a quick ((scale + extrude) – extrude) expression gave the CAD model for what you see below (outer shell – inner volume that slides onto the remaining handle). Printed, and.. perfect fit!  We still use this.


Shopping cart replacement clip

Long time ago, we bought a folding shopping cart from Amazon.  These are great, except for one thing: the little plastic clip that holds it in the folded position has a tendency to fall off.  We finally lost the clip on the way to the supermarket.  Unfortunately, you can’t buy just the clip, and without it the cart won’t stay folded.  But, with a 3D printer, the solution is easy enough: measure the wire diameter with calipers, then a union of two cylinders and a cuboid, minus two cylinders and another two cuboids for the insertion cutouts, and… done!  In the photo, I quickly printed an arrow on a label printer, to indicate the side with the slightly wider cutout (easier to insert/remove, the other one is a very tight fit, in hopes that the replacement won’t fly off as often).  Printed in ABS for a little flexibility, works better than the original!


Cat door and latch

We don’t allow our cat in the bedrooms, but with the doors constantly closed, I sometimes felt like a prisoner.  So I decided to try making a “cat barrier door”.  I wanted this to fit outside the door proper, and be as minimally invasive to the door frame as possible. I used mosquito net frame extrusions and wire mesh to make the “door” (it needed to be strong enough for just a cat, so that was fine).  I used Japanese double hinges to mount it, and 3D printed clips to hold the hinges to the frame (easy: a difference of two cuboids to make a Π-shaped solid that fits over the frame, and is wide enough for the hinge plates).  I also needed a latch, but unfortunately I couldn’t find one that would sit flush enough to the frame.  So, I designed one: two parts make the casing, leaving a hollow channel where a third piece (with the latch tongue) slides up-and-down, tensioned by a small spring.  A quick spray with teflon lubricant made it slide super-nicely.  A pair of cheap neodymium magnets (one on the frame, one on the latch) hold the door closed.   Works great, strong enough for a cat (but humans did accidentally break it a couple of times; no big deal, you can always hit “print” for a replacement).

The barrier door worked fine for the cat for several months. However, once my daughter grew up, she figured out how to open it (but was too young to understand that she should close it again), so the cat would come in.  Hence, I have since removed it, and don’t have any pictures of it mounted.  Instead, here is a render of the CAD models.


Door hanger hooks

We always had hooks over doors, to hang stuff (e.g., towels in the bathroom).  However, our current apartment has doors which are nice and solid but, unfortunately, much wider than most.  So none of the hooks we had would fit, and I couldn’t find anything that would fit in any of the usual places (Target, Home Depot, Amazon, etc).  So… I just printed one.  While at it, I made the CAD model parametric (aka “customizable”), so people could easily adapt it to their door (or to other inventive uses!).  Although a very simple model (ok, it might have taken a little more than an hour to parameterize it, but not much more), it is also my most remixed design.


Play yard fence legs

When my daughter was really young, we got one of those accordion-style play-yard fences.  We used it to separate a section of the living room, with a long, straight stretch of the fence.  Some members of the family were concerned that this long stretch was too wobbly.  So, I quickly whipped up these support legs, which tightly clip onto the fence’s frame.  Obviously they don’t provide structural support if someone were to, e.g., climb the fence (just saying… :), but they did stop the wobble and rattle quite successfully.


IKEA Besta rail stops

An easy “baby safety hack”: when my daughter less than a year old, she discovered a game: slamming the IKEA Besta sliding doors.  In order to prevent her from doing that (and pinching her finger), I quickly measured the aluminium channel dimensions, and made a tab that twists on tightly.  Took a test print and minor re-iteration to get it tight enough.  Works great, very unobtrusive.


Door stop pinch guard

Yet another “baby safety hack”: A plastic piece that slides into the door lock hole, and has a protrusion long enough to prevent the door from closing.  That was for when my daughter was a few months older than for the previous hack, and discovered the game of slamming room doors.  I remember that I actually whipped up this CAD model while holding my daughter on my lap (trying to prevent her from slamming the doors), in something like 10 minutes (later, I added a small hole on the handle, so we could tie a string and hang the thing from the door frame).


Other things

The above selection is rather random, and far from exhaustive.  Other quick hacks that come to mind, and not shown above: ethernet switch wall-brackets, embossed name tags for daycare, replacement water bottle cap, a customized shape-sorter toy, a slide-on button cover for a Nexus 7 (to prevent babies from hitting the home button and getting upset :), replacement tube guard-cage for a headphone tube amp, etc. I’m sure there are more that I forget.

Of course, there are also “hacks” that either took much longer than a few minutes to design (mostly stuff that needs to fit existing parts tightly, which takes a bit of trial-and-error, with a few test prints and re-iterations), or are relatively special-purpose.  For example, various enclosures (for, e.g., 3D printer, home-brew network video recorder, BusPirate, near-field mic), PSU covers, button faceplates, drawer knobs, mitre box, various jigs, OpenBeam cable clips, spool rollers and holders, iPhone dock for my car, adjustable clamp-on iPad stand for stationary exercise equipment, etc.

Finally, there are a number of things that I did not design myself but I found on the web.  Some examples that we use all the time are a cool “keychain”, laptop stand, stroller clips, bag clips, solder spool holder, etc etc.  Then, we naturally also do plastic toys and trinkets (the “novelty” aspect, which has been a hit with my daughter… those cute darn squirrels, for example). And, of course, I had to use the printer to build.. another printer (isn’t that what everyone with a 3D printer uses it for, sooner or later? :) It’s a modified Kossel, which has been working great for the last year; perhaps some day I’ll post about that “adventure”. :)