step one is to drill a hole for the magnet

it’s important that the magnet fits tightly in the hole you drill - so maybe you need to find half size drill bits. 7.5mm for example

the type of wood makes a difference too

in a soft wood you can drill a smaller hole - the wood will expand when you push the magnet in

a harder wood, or harder material - like glass or a rock - won’t expand , so if the hole is too small you’ll have to sand a few mm away - wrap / tape sandpaper around something cylindrical that fits in the hole

when you’re drilling the hole - if the wood is very soft like pine, be very careful not to let the piece move side to side, otherwise the hole will wallow out and become too big

it’s possible to drill the hole the correct size and insert the magnets without any epoxy and they will stay and be fine

wood absorbing water and changing shape with humidity - these are things that could be problems and cause the wood to crack someday

the depth of the hole is something else to consider. the magnets will have the strongest connection if they are flush, touching each other

the last thing to think about is the polarity of the magnets and making sure you are installing them in the attractive direction if you want them to snap together etc.

ok drilled the hole and have the epoxy mixed already.

i think the only tip is not to coat the entire inside of the hole with epoxy - and not to fill it too much- don’t fill the hole like you would fill a bucket with water - fill the hole like you are cleaning the inside of a bucket with a wet sponge

if there is epoxy on the entire inside surface of the hole, when you go to insert the magnet, it won’t push into the hole because it’s making complete contact on the sides and there’s no where for the air to escape

just coat most of the inside of the hole with epoxy, but leave some place untouched so air can escape and you can easily push the magnet all the way to the bottom of the hole

use other magnets to insert and remove the magnet you’re installing

after the magnet is in the hole push on it with something - in this case a pencil

then wipe away the epoxy

and be patient and let it dry 24 hours - or at least 6 hours. if you wait 2 hours the magnet will pull out and you’ll have to do it all over again. maybe put tape over it if you need to test something and the epoxy hasn’t set.