Summary

I've printed it to work with blind kids.
How else you can teach what is diagonal? :)

Outer cube is 120mm
Inner cube is 100mm

Printed in two pieces and snaps together.

Print Settings

Printer Brand:

RepRap

                                            <p class="detail-setting printer"><strong>Printer: </strong>                     <div><p>Prusa i3</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>0.3</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>60</p></div></p>                                                        <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>Shell thickness 1.2 so it will not break</p></div>

Post-Printing

                <p class="detail-image"><img src="https://cdn.thingiverse.com/assets/13/39/41/e3/33/IMG-20160531-WA0018.jpg"></p>

Cube in two parts