It is the tradition in my family to buy my husband a Lego set to put together on Christmas morning. I saw this Lego particle accelerator by JK Brickworks, and thought it was perfect! (The very fun video for it on the Lego site is worth the click.)
I ordered all the parts for it, but I had to order the track from Germany, and it did not arrive by Christmas day (actually, it still hasn’t arrived). I gave my husband the rest of the set, so he could at least be entertained by it.
My husband has a 3D printer (that he built!), so he decided to design and build his own track. The cat was fascinated, and I think it ended up working really well!