I realised that 'Alice' (and all the other locos) will benefit from sanding gear when working the new extention at Pulborough in the wet weather, and so I thought I'd make a start on some sand boxes for her. I thought this might be an interesting process for other people as well.
(Not only has 'Alice' got bits and pieces made like this, but the Hymek has her diesel tank made this way!)

Engineering in the larger scales gives one the opportunity to use different techniques - that perhaps would be less appropriate in the smaller sizes,

One example of this is the method I tend to use for making boxes - lubricators, sand boxes, fuel tanks etc.. In fact anything that could be made by folding cardboard!
In an ideal world, if you want to make up a box or tank in steel, you would fold it to make the easiest and neatest job. Most of us (me included) don't have access to proper folding equipment - and even if we did, it probably wouldn't do what we wanted. So folding steel is usually not an option. However, with the use of a mig welder (or gas welding) the job becomes really simple and very effective.

The technique is to mark the developement (as they used to call it at school) of the box or tank onto the steel sheet, and cut it out - I use either my band saw (in vertical mode) or a plasma cutter - and cut nearly all the way through the fold lines as well.

I leave half an inch of metal intact on each fold line, which is enough to keep the whole thing together. From that point (don't bother cleaning up the cuts) the whole thing can simply be folded to shape as you would a cardboard mock-up - and then tack each joint when you are happy with its position and squareness!

You are then left with 'open' joints, which are easily seam welded (at a suitably low amperage), and then carefully ground down to form neat and square corners.

All this is significantly easier than trying to hold together and tack separate bits and pieces in the conventional way, as when folding and adjusting it all actually stays where you put it!

The developement took half an hour to cut out on the band saw, and the folding and tacking took a further ten minutes. As soon as I've had a chance to weld and dress it, I'll show you the results! .....For those in doubt, 'Alice's saddle tank is welded in this way (but without the folding) and that looks fine!