I think I have an idea that you might like. Get a case, and then I’m not talking about a yoyo case, I’m talking about a completely empty one. Go to a store where they sell foam. If you get two layers of foam, you won’t have to do some of the harder and precision work. It is good to get layers that are around the thickness of your widest yoyo. It does not have to be thicker though. Then it might “swallow” your yoyos. Now you can start to make your own case.
First of all, you have to decide if you want circle or star shaped holes. Note that star shaped holes might be a bit harder to cut out depending on what tool you are using. Now make sure that the both of the foam layers you’ve gotten fits into your empty case. If it does not fit, use a pen knife or an exacto knife to cut the foam in the right size. When the foam fits, you can start on the next step.
Note that the following instructions will go for circle holes. Get a few opened tin cans. These tin cans should have sharp edges because these are what you actually cut the holes with. Now compare the tin cans to your yoyos. Foam is stretchy, so if you want the yoyo to fit snugly, you should find a tin can with a diameter a bit smaller than the yoyo itself. Please note that you may have to use different tin cans for different holes.
Now that you have found the perfect tin can you can start with the cutting. Find a suitable place in one of the foam layers. To cut the hole, place the tin can where you want the hole to be. Now start rotating the tin can straigh down the foam. This should make a nice hole that your yoyo will fit in.
If you want to have more holes, just make them. But remember to use tin cans that is in the right proportion of the yoyo you are making the hole for. If you want star holes, you will have to mark the shape of the hole (cookie cutters are the perfect shape) and then take a pen/exacto knife and cut the whole straight down. You want to make the hole as straight as possible.
You can now fit the layer without holes in the bottom of the case. This layer is supposed to act as a “floor” so that your yoyos won’t touch the real bottom of the case. Then place the layer with holes on top of that. I have heard that some people prefer to glue layers together. This might be a good idea if the top layer pops off when you take out your yoyos. If you don’t want to buy two layers, you can cut the holes in a certain depth, but then you have to be careful and not cut too deep. The good thing is that you can sutomize the depth. If you want to, you can get a laye of the cool bumpy foam. This can be used in the lid/top of your case.
Addment: If you really want a YYE case, stick some YYE stickers on the one you made.
Second addment: If you find any missing information in this post, tell me. It’s one hour until midnight here so I am a bit tired.
Hope I could be to any help.