I have been planning on putting this up for the past several weeks and finally got the time to do it, so here is my first online tutorial.
I have been using magnetized bases for my armies since back around 2002ish. I have went through several variations. First was using magnetic sheets and washers glued to the bottom of the bases, it provided some heft to the model but never did really stick as well as I would have liked. Then I found GF9 (Gale Force 9) magnetic bases and used them for several years.
GF9 bases have several advantages that I can see. First is that they are ready to use right out of the bag. Second is that they have every size you may need for a army. The downsides are cost, not that they are that expensive, but they do cost more than what some people are willing to pay and sometimes its difficult to get basing material to stick to the tops of the base. I personally never had this problem but it is something I have seen around the various forums I visit.
The reason I stopped using the GF9 bases was basically my own stupidity. I was trying to finish up a dwarf army for a tournament and needed to get the bases for the army ready. So when I got home one morning after getting off work, I decided to clean up the bases so I could finish them up the next day ( I usually cleaned the excess magnet of the sides of the bases to make them look a bit better when painted). I went through about 100-120 dollars worth of bases and went to bed. When I got up I went to get the bases ready for priming and noticed I did not have on single base that was the same size..... Damn, lesson learned
I did not want to spend another 100ish dollars on another set of bases so I got to looking around at what I had. And this is what I came up with.
Bases (of course kinda hard to make magnetic bases without bases)
Magnets (these are the ones I use)
Gorilla wood glue
Gorilla super glue
I originally tried to use epoxy resin, but it is awfully messy to work with, and I found that the combination of super glue and wood glue hold up just as well. I have not lost a magnet yet in about 5 years of using this method. Of course now since I said that I will pull my army out next time and all the magnets will pull off...
Find a good place u can work from and don't mind having a stack of magnets around and glue a magnet down. This will allow you to keep the polarity for all your magnets facing the same direction. After this one is set, all you do is pull the magnet directly off and set it inside the base. I don't even worry bout flipping the magnet, all you want is the polarity to be the same on each.
Place a drop of glue in the center of the base and place the magnet onto the glue. Be careful not to flip the magnet. I still do this occasionally and it takes some patience sometimes, especially when you are doing multiple magnets under a larger base. I also sometimes use a zip kicker or something similar to quick set the super glue.
Place a drop of the wood glue on each magnet, and then spread it out using a wood applicator of some sort (Popsicle stick, toothpick, etc.). You want to make sure that the glue does not stick up over the edge of the base or the base wont sit flat on the table. Once you get the hang of it you can do several bases at a time, I usually do between 6 and 8.
(not the greatest picture)
Set the bases aside to dry overnight, I usually do all this on a couple cheap plastic plates I picked up from the clearance section at a local mega-mart.
Really no step five, except place your model on it and continue as normal.
I do still use the magnetic basing inserts from GF9, but you could use anything from sheet steel, sheet metal, maybe even magnetic paint (though I have not tried it, if you do and it works let me know)
So that is how I do my magnetic bases, I hope you enjoyed the reading. Any questions, comments let me know
Just a head up I modified something in this guide, click on the magnet label and it should pop up. But the general gist of it is, instead of using wood glue, I am using Realistic water to secure the magnets. the wood glue causes the magnets to rust over time.