Scale it to your needs and make yourself a weighted companion cube to be a nice penholder, paperweight, desktoy or trow piece out of clay, concrete or even playdoh.

Assembly:
This step is not neccesary but it makes assembly much easier. 
Put the Mold pieces togehter with duct tape

Afterwards, put the Top and Bottom piece in place and roll everything together.

The mold will be held in place by sliding the Retainer on the top and bottom. Use more duct tape to make the space between the mold and the retainer as smal as you can get it.

How to use
Make smal beads out of clay (or similar) and start filling in the corners first. The rest will basically fill in it self. Make sure you apply enough preasure to make all the details apear. If you are done, put some material on the Top_Insert piece and close everything up. Slide the retainer off the ends and CAREFULLY remove the rest of the mold. The first few cubes might dont look so pleasing but you'll get it realy fast. Making these i had more fun than it should be legally allowed for an alleged adult human beeing… 
If you dont want to have a paperweight (aka 360° nice to look at cube) dont insert the Top_Insert piece and make a hole in the middle instead. By this you'll create a penholder, paperclip storage, container for pencil shavings or even an ashtray

Note:
If you want to use concrete instead of clay, you'll have to apply some sort of mold release in order to get everything out. The concrete it self should also be realy thick so it wont leak out of the mold. If you glue everythin together, you can use it for more liquid materials and casting of course

Did you know? It makes also for great companion 

While commuting to work
 

During vacation

…in your bed