[MaciekA]

Another thing that makes mechboxes easier to close is short springs, like on DBoys mechboxes (for example).

With respect to very strong and bendy springs, I use a very narrow Torx screw driver and insert it into the spring guide. Then, if the spring is so bendy that it makes the piston and cylinder pop out, I'll bend it downwards to straighten out the spring while grabbing the other half of the gearbox shell. Stick your index finger through cylinder window so that you can use that finger to press down on the piston and seat it in its groove. Then simply lower the shell down and use the left end to grab the spring guide tab. Focus on the spring guide tab seating into its groove properly and "wrapping" the shell around the cylinder head on the other end. The gear shafts are always a piece of cake after this (using the method mentioned way above, with a tiny flathead adjusting where the shafts are while pressing down hard).