Many bees are making methylamine out of hexamine and HCl acid. I think it's very time consuming and HCl is pretty nasty. Thus I have found that one can easily make lots of good quality methylamine from ammonium chloride and formaldehyde (formalin). Only drawback with this method is that one must have good quality formaldehyde. It may have paraformaldehyde sediment in the bottom, it doesn't hurt, not even a bit, but Formaldehyde has to be strong and not some diluted shit, 35-40% is fine.
Now to the more-less foolproof method. If you do like said below, you get around 400-450 grams of pretty pure dimethylamine-free methylamine hydrochloride which is perfect for Al/Hg reductive aminations.
Chemicals needed:
1100g of Ammonium Chloride
2 liters of 35-40% Formaldehyde
about half a litre of chloroform