Here is something bizarre yet fun. Masterpiece Soundwave's release through Amazon in Japan comes with a special, clear Energon cube accessory. What Takara-Tomy has released as a special bonus is an insert for that cube to represent when the Decepticons "filled" the Energon cubes with energy plundered from Earth. It's a free download available from their site, and doubtless there's a possibility here to make some custom Energon cubes to display with your Transformers.
The Takara-Tomy campaign page is here
A direct link to the PDF download is here