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The MoA and AoA (short forms for Memorandum and Articles of Association respectively) are drafted by solicitors. I think the best way to do it, is through your Company Secretary who already knows well what you want and what you need, and for sure will be in contact with a good solicitor who can do the job within your budget (considering the fees of the CS are already within your budget, of course).
The MoA and AoA are quite important for the future development of your company. They
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For instance, if you are planning to set up a company to sell pencils, don't write just pencils in your MoA and AoA. It would be better if you write manufacturing and selling of stationery items, paper making and recycling, printing, publishing, etc, i.e. all kind of related activities which one day may fall in your sphere. The idea is that, when more business opportunities come your way, you do not be constrained by something as small as this. I guess you would just have to re-draft the MoA and AoA, but why to take the trouble if you can avoid it?