Creeper Paper Clips (3D Printed)

After my daughter decided that the Heart-Shaped paperclips were a great gift for her friends for Valentines day, she realized that maybe the boys in the class should have a non-heart option.

We 3D printed a few of the Superbowl football paperclips as an option, but then came up with another idea - Creeper Clips! These have the face of the popular Minecraft (tm) creature called the Creeper. It's a simple pixelated creepy face with a paperclip base.

Design Approach

There was one interesting thing about this model that's worth sharing (besides the paperclip part which I've already over-used). To get the multi-color pixelated look, I created different thickness areas on the face of the model.

original with tiny 2.5mm pixel size

To do this, I simply made 2.5mm by 2.5mm square tiles that were 0.4mm thick, and randomly (but evenly) pasted them on the base model in depths of one or two tiles. That resulted in a model which had 3 depths, each of which lets through a different amount of light and therefore gives the appearance of multiple shades of green - giving the Creeper quite an authentic look!

Adjusting the Model

Turns out the tiny 2.5mm blocks don't print that well at speed or when printing many copies at the same time. I adjusted by doubling the size of the "pixels" to 5mm squares, and got a much better result without sacrificing the look of the final print.

different height pixels colored for visibility

I also created a larger size by simply scaling up, which also increased the size of the original pixels to 3.25mm, which also worked pretty well.

The final adjustment was to give more space between the inner shape and the clip. I started with 1.5mm, which tended to crease or cut the paper that it was clipped onto - so I increased it to 2.6mm for a much better result.

The Model

Here is the Creeper Clip paperclip model. Print a few dozen to give away to your Minecraft fan friends!

Multi-Color #3DPrinting - using Sharpies (tm)

Most reasonably priced, and many fairly expensive, #3DPrinters print one color at a time - which practically means that most objects you print will be a single color. Boring!

One technical way to get multi-color is sometimes expensive and still limiting - that is to get a dual-extruder, where two colors can be loaded and printed during one print cycle. Our school tech club has a FlashForge dual extruder, and while it's cool, it's still limiting - allowing exactly two colors.

Another way to get multi-color #3DPrinted objects is to design models which are multi-part so that each part can be made in different colors and then connected. This is my preferred method so far - but it is truly hard to design in 3D Modeling software with this in mind.

Of course there are much more expensive printers which achieve not only multiple colors, but even full-spectrum color, like your desktop paper printer does. But with the types of 3D printers that most of us have, I found another, more crafty (some might call it fake) way to achieve multi-color - that is, to print your objects using white filament and then use Sharpie (tm) markers to color the models any way you want. What I like best about this method, is that it requires some good old-fashioned arts and crafts action - drawing with your hands (imagine that!).

I've experimented a bit with this, and so far it works pretty well. Included in this post is a video (quick time-lapse) of me coloring a miniature version of my custom designed Minecraft (tm) TNT block. I found that using Sharpie's for even minor highlights really makes some models look significantly better. When I print that same TNT block in pure red - it's hard to see the letters or the other details, like the fuse on top, which I can now color in black.

My experiment with the Minecraft (tm) sword shown in the images in this post was circularly inspired by my friend Alice Keeler's post where she suggests using spreadsheets as a pixel art creator - and she showed an image of a pixel-art Minecraft sword. I used that design as a guide to try coloring my own #3DPrinted Minecraft Sword... Not too shabby (ok, a little shabby).

The before (white) and after Minecraft(tm) Sword!

3D Printing Custom Made TNT Block

The Minecraft (tm) theme seemed like a good one to start with when looking for fun things to print.

The short story

I created a model of a TNT block which my printer could handle (see longer story below to see why) - printed it - and posted it on Thingiverse as "TNT Block". It has 84 downloads in 10 days - so not too bad.

The longer story

I first found a TNT block on Thingiverse created by someone else and it looked really cool.

FAILED print - stopped part way.
Notice the strands which fell.

I tried to print that one - but there were problems. As you understand how a Fused Deposit Modeling (FDM) printer works - like mine and most of those you see today in the retail space - you can see why "overhangs" might not work too well. Each layer needs something under it to support it. You can have angles, but not 90 degree overhangs.
The TNT labels on the side of this model I found were definitely not friendly to my printer - and as soon as the TNT labels on the 4 sides started to print, the problem was clear - the extrusion was falling off the sides rather than sticking to the model, because there was nothing under it to hold it up.

So - in my model - I created a subtle slant to every overhand - so it still stuck out the side, but with enough of a gradual slant to support the material as it was extruded.
Summary - it takes some time to create a model which will print on an FDM printer and some problem solving during the modeling process to get the results you want.

Scaling down a model for (much) faster 3D Printing

Those Minecraft (tm) tools I printed were really a big hit (with the kids) but they were quite big - The shovel came out at about 96mm (3.75 inches) - so you can imagine the charms were a bit too big for a keychain - about double the size and volume of a normal house key. I call them BackPack charms for that reason. The other problem was, they took a dogs age (whatever that means) to print. Those original set of 4 tools (all in one model) took almost 4 hours!

But what if I scaled them down in size? Would half the size take half the print time? I decided to experiment. I scaled down the tools to 3 different sizes to see what the effect was on size, print time and appearance. I used the Slic3r app to do the scaling - meaning I used the same source .STL model that came out of Autodesk 123D and scaled it 3 different times to generate 3 new .gcode files for my printer.
I printed at 100% (the original print), 50%, 35% and 25%.

Size

This was simple and accurate. The dimensions of the scaled down model were exactly scaled to the target ratio. For example - The original shovel was 96mm long, the 50% scaled was 48mm long. The 35% shovel was 34mm, the 25% was 24mm. Perfect. That said - visually, those scaled down versions looked unexpectedly smaller than their ratio due to the uniform scaling of all 3 dimensions - there was just less heft/volume overall - but they were accurate when measured. The 25% printed versions were miniscule

Print Time

This was not obvious, but the results were very encouraging. The reduction in size for a model scaled to 50% is much less than half the time - in fact, the 50% scaled print took 15% of the time. Rather than 238 minutes, it took just 36 minutes! This finding would impact my early prints of almost everything from this point forward. My next quest will be to come up with a semi-accurate estimation formula of print time. I'm sure that's achievable.
UPDATE (2/2/2015):  This might be a good place to use the "Square-Cube Law" - which states (among other thigs) that "...new volume is proportional to the cube of the multiplier." - which applies to the print time too, perhaps, since the cube of 0.5 is 0.0625 (one eighth) - so 238 minutes, at 50% size predicts a print time of 14+ minutes (actual time was 36 minutes, so this still needs some work).

Data

The 3D model of these tools can be found on Thingiverse.com. I did not create the original model, I just enhanced it to have keychain holes in all the handles.


(yes, Minecraft is now probably a trademark of Microsoft, inc.)

3D Printing Minecraft (tm) Tools as BackPack Charms

I found a fun model on Thingiverse.com that included 4 separate objects in one file - four Minecraft (tm) tools. The only problem I had was that, once printed, they couldn't be attached to anything. So, given that Thingiverse.com encourages "remixing" models, I pulled this one into Autodesk 123D Deisigner and punched keychain holes into the handles of the Sword, Shovel, Axe and Pickaxe.

I re-uploaded that remixed model on thingiverse - so now you can use the Diamond Minecraft Tools - Remix with Keychain Holes too :)

The original model was great - but I really wanted those keychain holes.... and it worked out.
These printed rather nicely - measuring around 4 - 4.5" (100cm) each with some nice thickness. Attached to a backpack of a 6th grader, they're impressive.

The print was a bit long - over 4 hours, which inspired another project - to attempt to print at smaller sizes just to see the impact (look for that in a later post.

Some Print Details:

Filament:  JET PLA Orange 2.75mm (actual)
Model:  Diamond Minecraft Tools Remix
Time to Print:  3 hrs 57 min.