Summary

It's a better keyfob to hold F3 or F5 iButtons on your keyring. It's curved and it just feels nice :)

Print Settings

Printer Brand:

Ultimaker

                                            <p class="detail-setting printer"><strong>Printer: </strong>                     <div><p><a rel="nofollow" href="https://ultimaker.com/" target="_blank">Ultimaker 2</a></p></div></p>                                                                                <p class="detail-setting rafts"><strong>Rafts: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting resolution"><strong>Resolution: </strong>                     <div><p>0.15mm</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>100%</p></div></p>                                                        <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>I used PETG as the material. PLA works as well, but PETG's flexibility makes it stronger.</p><p>You can change the shell thickness to 2.4 to save a lot of time in printing. If you do this, the infill setting barely matters because most of the material is the shell now :)</p><p>Version 1.x is rotated 105 degrees to put it upright on the bed. Version 2.x is printed on it's side.</p><p>When editing the thing in OpenSCAD, you may want to set $fn to 32 to save render time when previewing and set it back to 128 for the final render to STL. The hull() takes quite a bit of effort.</p></div>

How I Designed This

RevSpace

            <div><p>I just became a member of RevSpace, a hackerspace in Den Haag (The Hague) in The Netherlands. Our Doorduino uses iButtons and those come with pretty standard keyfobs like these.</p></div>                <p class="detail-image"><img src="https://cdn.thingiverse.com/assets/1c/b7/18/a5/70/DS9093F%2B.JPG"></p>            <p class="detail-caption"><strong>RevSpace keyfob</strong></p>                <div><p>They aren't as sturdy as they should be (a part of mine broke off and I had to duct-tape it). And because it is flat, it is not very easy to press it against the reader.</p><p>The upside is that you can easily swap the iButton for another one.</p></div>                <p class="detail-title"><strong>DUWO/Salto</strong></p>            <div><p>I live in a student dorm, and the place has iButton-like keys for the building front door and each floor, and the indoor bike shed (being dutch all the way ;) ). They are made by Salso Systems. This keyfob looks like this one:</p></div>                <p class="detail-image"><img src="https://cdn.thingiverse.com/assets/92/b0/8d/e1/c3/salto03.jpg"></p>            <p class="detail-caption"><strong>Salto keyfob and scanner</strong></p>                <div><p>These are much more sturdy (I'd say unbreakable). Because they are curved, they are easier to scan.</p><p>Downside: you can't swap the iButton for something else.</p></div>                <p class="detail-title"><strong>I fixed it!</strong></p>            <div><p>I took the best from both designs. Curved and sturdy like the Salto, and replaceable like the original RevSpace fob.</p><p>I fired up OpenSCAD, and tried a few things. At first it was hard to get the position on the print bed right, and my first attempt had ugly support stuff everywhere. Also, my first version was too thing ans very flimsy.</p><p>But then I tried it upright. By accident rotated it not 90 but 105 degrees, and that turned out to be just perfect. No supports needed!</p></div>                <p class="detail-title"><strong>Version 2.0</strong></p>            <div><p>or that is what I believed for a while. I printed a few and some of those broke because the 1.x design depended too much on layer adhesion to stick together. I changed the design to have a flat side and printed it sideways. This is version 2.0. It seems to be a lot stronger now.</p></div>                <p class="detail-image"><img src="https://cdn.thingiverse.com/assets/e7/e9/9b/7b/19/IMG_20160524_004130_e.jpg"></p>

iButton keyfob