Hmmm... maybe a contest on designing steem-themed 3D printable models ?
Like a steampunk locomotive with the steem logo and address (er even a QR code on the bottom of the model)

I think there's potential in that...

I'd personally organize such a contest as divided into 2, each steem-themed but also an additional theme (steampunk for one and futuristic for the other, for example). (each model, to guarantee uniqueness, would have your steemit username and a QR code for donating to you... then I'd need to think up how to be SURE they're relatively original submissions, and not just a model from some other creator with the steem logo plastered on it)

The prizes would be 15 SBD for first prize and 10 SBD for second prize. possibly adjusted a bit so there's the possibility fo rewarding those that went above and beyond and actually printed (and provided print instructions for) their 3d model.

The winners would be chosen by the community.
or maybe I'd harass some of the good people on steemit who have already designed promotional steemit material (I'm looking at you @papa-pepper XP) to help as a panel of judges for 1st prize, and have the second prize be who the community votes for (if it's the same, then whoever got the next-highest votes).

There's lots of variability possible. Have a Remix competition where you need to take 2 models from a given set of open-source full-reuse-possible 3d models and remix them, then apply some Steemit branding to it...

Just my proposition (IF I'm chosen, I wouldn't know where to start to properly organize it... but you asked, so I answered XD)