But on the legal side manufacturing just means "to make", which is all you are doing.
If you want to risk it, and have a potential visit from the police, go ahead. I myself am quite happy inside the law.
If I was you, I'd go to 3 games in the 56 days(or 2 months) get yourself UKARA registered, and then voila, no more problems, unless it's firing hot, then be prepared for jail time!