All kinds of things can be used for markers… the little plastic clips from bread bags, twistie ties, bits of contrasting yarn, pipe cleaners, even drinking straws.
I use scissors to clip narrow rings from different colors of plastic drinking straws (clean ones, of course). But you may want to do that into a shoe box or inside a gallon size baggie, as the small rings tend to shoot all over the room.
If you want to get REALLY fancy, go to the craft store and get some of those sparkly type pipe cleaners and cut pieces to the size you want. Or some ‘french wires’ for pierced earrings with small beads, pinched slightly closed to stay on the needle after clipping or slipping them on.
If you can look at a picture of something knitted and say “I can make that”, then think about what you need to do it, and make what you need. Maybe I’m just cheap, but I don’t need to spend when I can recycle.
Personalize your tools, and you can say “I made this with tools that I made”. Get crafty with your craft… so to speak.