New folks ask this a lot. So here's one post with all the links in it.
Step one:
Print yourself some markers.
I like this link, from ToadChild: Infinity Marker Sheet Creator
If you are new to the game and want to be sure you don't miss anything basic, you can go to the official CB site and get these:
Infinity Markers Letter Size Also in A4
Suggestions: Print on cardstock. Not 100% necessary, but you want something that's going to stand up to your punch without tearing. Also, if you use the double-sided method, you want something that's not going to discolor when you glue the markers together. I also recommend printing in color, it's more expensive, but makes things easier to recognize on the table.
Step two:
Punch 'em. I use one of these: Fiskar 1" round punch But a quick google search or inquiry at a local craft store will come up with lots of alternatives.
Suggestions: When you punch, some white is going to show through where the punch cuts out the markers.
Grab a black marker and color this edge back in. Takes 2 seconds on each marker and really improves the look. I've seen some go hog wild and color the whole back of the marker black. That looks really nice.
Step three:
Stick epoxy stickers on 'em and mash 'em with your thumb. I'm klutzy so I tend to get real careful about lining up the marker and the sticker. I hold the sticker and the marker between three fingers of my left hand, and then pinch them together with my right hand to stick them on. That's worked well for me. I haven't had to pull a sticker off of a marker yet due to bad positioning, but I'm fairly sure it wouldn't go well.
I buy these in lots of 200 from Beadaholique They are intended for use by bottle cap collectors and jewelry makers, but they serve our purpose just fine. Costs about 7 dollars for 200, which is more than enough to share.
Want something even nicer but still inexpensive: Warsenal makes clear acrylic discs. I saw a set of markers made with these online and they looked super nice. The only ones on the Warsenal site have holes in them for use as flight stands, but an e-mail might get you a custom batch with no holes.
Rinse, repeat until you have all the markers you want. I made over a hundred in less time than it took to watch 2 episodes of The Flash.
Final thoughts:
The epoxy stickers tend to stick to each other. I actually like this, as it makes it easy for me to get, say, 10 order markers out of a pocket of my tray all at once instead of digging for them with my fat fingers.
Double-sided markers are a thing. A drop of white glue and a few seconds of pressure and your two new markers are now 1 double sided marker.
You can put, for example Burnt markers on the back of all your camo tokens. Impersonation-1 and Impersonation-2 together. I put Unconscious on the back of my 1 W markers for HI. It works with markers that are used together and markers that aren't. I play combined army and nomads. Nomads don't get Sepsitor, and Combined Army doesn't get Deployable repeaters. so I stuck them together to simplify organization and make things easy to find in the heat of battle.