Oh, goodness, I have quite a list! My state was one of the first to declare a stay-at-home order, and my parents were keeping me home even before that (since I was on spring break), so I have plenty of suggestions. Let's see...

#1 Learn how to sew. Sewing is a skill that will definitely come in handy as you grow up. If an item of clothing gets ripped, you can fix it, or if you don't like the way something fits you, you can tailor it! I've been branching out into major things lately (cropping, turning a dress into pants, embroidery, etc) but you can always start small if you're unsure of your sewing abilities.

#2 Learn how to do origami. Origami can be time-consuming, but it's also very rewarding! My biggest advice for this is to start with something achievable. If you want to replicate a super-complicated piece of origami you saw online, that's cool, but maybe start with something smaller first. If you try for something too far out of your range of ability, you might get frustrated and want to stop.

#3 Build a miniature. I've been working on a miniature bookstore lately, and it's honestly so much fun! It can be challenging to work with all the little parts and pieces, but the end result is amazing. If you don't know what a miniature is, it's basically what it sounds like-- a small, to-scale model of something. Most people think of like model airplanes and such, but there's so much variety out there. You can order one online anytime. Just be patient and somewhat organized, and I think you'll find it's satisfying and hypnotic.

#4 Re-design your room. This one is pretty self-explanatory. It doesn't even have to be anything big-- maybe you just switch around a couple of posters or something. Even making little changes can make you feel accomplished.

#5 Go through all your clothes. You know all those t-shirts that you got from events that you never wear anymore? Or those jeans that never fit quite right? Go through your closet and keep only the stuff that you really want to. This also plays into the leanring how to sew thing. If you really like a piece of clothing, but it's ripped or torn, figure out how to fix it! Or maybe you think a t-shirt is too plain, so you sew some patches onto it, or embroider some flowers. It's up to you! 

#6 Go for a walk. Make sure you keep away from other people (I'm assuming you're under a quarantine and need to social distance) but getting out of the house and into the fresh air feels so good and just rejuvenates you. Even just going out to your backyard or porch or balcony or wherever can help. 

Alright, I think those are most of my tips-- I have more hobbies, but a lot of them involve going somewhere or you need special things to do them. Good luck, have fun, and stay healthy!

~Starseeker 

I'm gonna go learn LotR Elvish! Then I'm going to speak in an Irish accent and see how small I can write. After that, I'm going to draw axolotls on sticky notes and hide them in small places and see how long it takes my parents to find them. Lastly, I'm going to write an essay plan. ugh.

-Rubik's Cubing! It's super fun to be able to solve one once you learn how to do it, and it takes a while to learn it at first but there are lots of websites and cheat sheets to help you. It's even fun to just use a Rubik's Cube as a fidget toy and move around the cubes. 

-And stretching! I've been trying to get into the habit of stretching every morning before I start the rest of my day. It's kinda relaxing and it feels really good. There are so many different stretches you do and if you stretch in the morning, you'll feel better for the rest of the day. I like to stretch my neck, shoulders, legs (working on my splits haha) and back. You can pick stretches that work for whatever you want to do 

-Core exercises--this is something you can just do whenever, and wherever pretty much as long as you have somewhere to lie down! Having strong core muscles helps with balance and strength and stuff. Doing core exercises also makes you develop abs :P You can do bridges, crunches, situps, planks, pushups, and supermans, and there are probably some others I'm not thinking of. I've been trying to do this every day as well, it's good for you and a good way to spend some time! It'll be hard at first if you're really doing stuff that's working your muscles and you're not used to it but if you do it every day it gets easier. 

-Hand lettering--learn how to do calligraphy/hand lettering, because it's fun and it looks SUPER pretty. There are bunches of tutorials online. 

-Sunbathing. Lol I haven't done this yet but I really want to. It feels so nice to lie in the sun (assuming there IS sun, it's been cloudy and rainy in Portland recently >:l ) so as long as you have a space outside that you can lie down on with a towel or something you can just lie in the sun. Don't get sunburnt though XD

-Do facemasks. I LOVE doing this. There are tons of facemasks you can make with really simple ingredients most people have in their houses usually, like honey and oats and bananas and cucumbers. Different facemasks can do different things, and they usually make your skin feel really good 

#1: @Starseeker suggested building minatures and I second that. That's been one of my main hobbies for a while. I like building all sorts of stuff but usually houses, with hot glue and spare cardboard. I'm currently working on building something like Rhosgobel (Radagast the Brown's house from LotR. It's not working perfectly, but it is fun, and time-consuming, yes). 

#2: Memorize poetry/theater. It sounds kinda cheesy but it's actually really fun. I'm doing Hamlet's To Be or Not to be soliloquy, partly for english class and partly for fun. But you could memorize anything, really. My family is putting together an effort to do a play recitation. 

#3: I know you're already on NaNo, @Cello, because of the CB cabin, so I won't suggest writing a novel...but still. 

#4: Play a *live* rp (with your friends or family or whatever), like D&D. Or you could make a dungeon mod to play an rp in, which is what I'm doing. I like it because there's almost endless possibilities and a lot of opportunities to create, and you can develop characters almost as much as you would in a story.

#5: Try something like simple filmmaking. There are a lot of free stop-motion apps available online, and a lot of them have cool effects like Green Screen and editing. I've been using Stop Motion and I like sculpting, so I've been experimenting with claymation. It's sometimes frustrating but it's really fun, and you can do all sorts of cool stuff. 

#6: Go on the CB, haha