Ideas for useful garden art (especially cardboard)

Hello world,

What are good topics, infographics, or doodle-worthy shapes and concepts which could be incorporated into fun but useful and/or informational garden artwork (preferably made out of cardboard)?  

Constraints:

The medium I'd like to use is simple, old, upcycled cardboard.

The cardboard might have fun, cut-out shapes.  

It might be painted with surplus paint from other projects, or blackboard paint to enable kids and adults to write on it with chalk as a kind of low-cost blackboard.

The cardboard will likely hang on a fence with garden wire for a couple seasons.  Then it will either be composted or recycled (if no paint/gick) or it will be tossed in the trash after exposure to elements and kids playing with it.

The cardboard might be made into 3D elements (for example, bean bag toss, or castles), but I want it to have an informational or earth-inspired aspect.

Temperate, wet, gray climate.

Basically, I am thinking of extrapolating the little cardboard info-squares concept I've previously used for a kids workshop, but larger in size, more diverse in shape, possibly 3D, and multi-audience (adults & kids, multi-ethnic and multi-lingual).

This art project is part of a larger urban-garden design project I'm calling the "Six Sisters Garden".

Current ideas:
-Composting "how-to" infographic
-Cycles
   -Water cycle
   -Carbon cycle
   -Nitrogen cycle
-Tree motif
-Earth/globe motif
-Gnomes motif
-Earth care, people care, future care motif
-"What do plants need?"
-Castle/fort form that kids can hide under
-Bean bag toss form that adults can play cornhole with
-Flip boards Q&A, or sequences or multiple  layers on top of one another (soil perhaps?)

An example of a complete concept:
-Cardboard upcycled into bean bag toss/cornhole forms with drawings of beans, and information about legumes on one board, contrasted with information about corn, fertilizer, and global agrochem usage on the other board.

Here's one useful + informational cardboard project:

Colorful instructions.

Rather than plain boring cardboard with a Sharpie, this one has a little bit of blackboard paint for its background, with colorful pops of color from chalk pens.  

The painted black layer is thin, namely because I was using this bit of cardboard to "clean" the residual paint off my brushes from other projects.  In other words, I tried to reduce wasted paint by putting it on the cardboard, something useful, rather than immediately soaking the brushes and disposing of the nasty thick murky paint water.  

From an artistic standpoint, the ripped blackened cardboard gives an aesthetic of it being charred with fire, which is appropriate for it being used in a future pyrography workshop.

Share seeds along with fun and useful information with this original concept:

Cardboard seed sharing info-squares.

How to make them:

Eat some sushi: I upcycle these small circular tupperware containers which come via sushi-delivery. They previously held wasabi and soy sauce, but now they hold seeds to share!

On old cardboard, I trace the bottoms of these circular containers with a pen.

With a knife, I cut starry zig-zag'd edges along the circumference of the tracings.

Using a Sharpie, and optional colored pencils or chalk pens, I doodled information about the seeds I wanted to share.

Pop those little seed saving nuggets into the holes, and voilà!

Now I can bring them to our seed-sharing workshop to pass around, or I can put them up on a fence with garden wire to serve as semi-disposable, temporary, guerilla seed-sharing artwork!  Some of them can be freestanding for a table-top display, too.

*EDIT TO ADD:*
I think it is important to acknowledge whenever stuff *doesn't* work, and why.  While my cardboard infosquares from a previous year lasted a good while, the ones in this post here didn't last but a week!  The main reason was heavy rain and winds.  Had this project taken place in a drier month or climate, it would have been more useful and lasted longer.