Hull lock.

[wibblywobbly]

One thing to remember is that when the upper and lower are screwed together they form a solid box section that won't flex. If they are held by magnets or whatever then the two halves can flex a bit. If you go the magnet route it is worth cutting a sheet of 3mm styrene and using a hot glue gun to secure it into the bottom of the lower hull, or screwing a sheet of alloy plate onto the underside of the lower.

[MichaelC]

I always use the 1/4" or 6.4mm diameter ones as they fit snugly on the lower mount. For the upper I would cut off 2 magnets worth (for 2 x 3.2mm) plus a little bit, it doesn't have to be precise. I then cut out aluminum tubes with ID of 6.7 mm (I think can't remember exactly but it has to be bigger than 6.4mm obviously) and glue the upper magnet on one end. After you prep all these pipes with magnet in one end, I then put 2 part epoxy in the open end and slide them into the upper mount.

You have to make sure that the upper and lower magnets are oriented the same way, and also you might have to clear the supporting flangs on the upper mount depended how much extra tubing you have cut. Once you have all the uppers fitted with the tubing with the magnets at the bottom, you can just close the two halves, and the lower magents will pull the upper magnet and tubing down to whatever position it needs to be. Since it is two part epoxy you will have time to settle. You can then make sure the two halfs are fitted properly, and I usually would flip the hull upside down and let it settle. The weight of the lower will make sure that the two halves are a tight fit.

Here is a pic showing the upper and the lower mounts with magnets.

[43rdRecceReg]

One thing to remember is that when the upper and lower are screwed together they form a solid box section that won't flex. If they are held by magnets or whatever then the two halves can flex a bit. If you go the magnet route it is worth cutting a sheet of 3mm styrene and using a hot glue gun to secure it into the bottom of the lower hull, or screwing a sheet of alloy plate onto the underside of the lower.

A timely caveat, Wibb. It's also worth noting that these powerful wee magnets can have a bad effect on your digital swatch, or smart phone if they happen to come in close proximity