Found these online:

Homemade Glue Recipe
This is a very basic glue but works. Simply mix water and flour together until you have a paste that is the consistency of pancake batter. Heat on low for 5 minutes. You can add color (food coloring) or flavors to it.

This recipe is non-toxic but it does take awhile to dry.

Here is another Glue Recipe

1 cup tapioca starch
4 Tablespoons of sugar
2 cups of cold water

Mix starch, water and sugar in a sauce pan until all ingredients are dissolved. Stir over medium heat until it forms a paste. This mixture should be stored in an airtight container that just fits the amount that you have left.

Was going to suggest same. Use a starchy flour like cornflour (cornstarch?) and water. Apply and let thoroughly dry. Though not ideal if a bunny eats it, if it does ingest a little, it wouldn’t be toxic, just extra carbs.

For a glue-free option, try using cable ties to fix some edges down to the cardboard.

I need to see pictures of the finished product! THat sounds cool!

You could also try and just zipties to secure it. Cut little holes on the edges and pull the zipties tight and cut off the extra.

Zip tie / cable ties are the plastic one you thread one end through other and pull it tight. I don’t know if the grocery store ties would stay – are these like bread twister ties? But something like that in a thicker, longer wire might work.

Or you could use some of these clips around the edge.   They are really strong and you can fold the wire bit back down so it sits flat on top of the mat.

Yeah, I doubt the grocery store twist ties would stay. Moose likes tugging on the bars to Monkey’s pen when they are running around, and she has a twist tie on one end that’s coming loose from Moose tugging. Luckily I won’t need that pen up much longer

I got a couple bags of those clips from the office supply place nearby.. shouldn’t be hard to find

I had a wooden “bench” that my husband made for Cotton to jump in and out of her original cage to get into her pen area.  I just drilled holes in the wood and used sisal or cotton rope to tie each corner of the mat down- and clipped the excess from the knot.  I did not want her slipping on the bare wood so I used a typical grass mat that is sold for bunnies.

Yea I love those clips they are all throughout my cage holding on mats. With that thought I really do need to buy the bunnies more sea grass mats. Maybe for their birthday I will, but the problem is that I look at the stuff on this website and I can’t just buy one thing! I put all this stuff in my cart and it ends up to be 80 dollars! And I can’t bear to take anything out of the cart…

Hehe my hubby makes sure to go through my cart before I’m allowed to click the button to get it all.. he makes sure I don’t over buy

Perfect!  BTW, Buddie is too cute to be real – he looks like the cutest bunny toy! 

see hershey’s earys look nothing like buddies!! and she’s a lionhead too… i love her but she isnt living up to her breed, she looks more like a big nethie than a lionhead… shes so small and her ears are so tiny and straight not wide and roundish like i lionhead

i met the parents when we got her we had a choice between hershey and her sister who looks identical (except with a mane) looks like a lionhead, her brother looks like buddy only in white with the blew eyes soo cute
we originally wanted the brother or hershey but they werent selling the brother, and my little sister wanted ther one that “looked like a bunny” so we got hershey

lol it must be a lion head thing, hershey thinks the world revolves around her

Seems like a nethie thing too

Pssst Buddie! You’re adorable! <3