Well lightbox is fine - but are you looking for most efficient and/or quality solution or perhaps most easy one
Anyway I'm afraid that there is no single one "gold" solution. But there is at least a couple of most commonly used techniques (although each one has some learning curve and needs practice, so no cutting the corners..
Well in fact the major goal while working on figurine's B-side is to achieve equal/matching A and B sides. At the end at least(!) figurine's A and B contours should match)
But remember that unless you are using no borders (white) or just thin single-line outline (which both needs almost perfect A and B side matching) there is some degree of "freedom". As black bordering gives quite significant space for most discrepancies and will cover even some minor errors - and that's IMO probably one of the main reasons why black and thick borders are so popular among designers)
OK, Back to B-sides.
Actually you can just hand draw these (no litghbox etc.). It's in fact fast and easy for less complicated shapes and figurines. It's also possible for even more advanced projects. But in most (if not all) cases some corrections and even resizing/reshaping is usually needed after converting sketch into digital version (scan/photo) - just to correct distortions.
Then you can use some techniques which are kinda similar to lightbox:
You can use transparent paper or tracing-paper (well it's almost exactly the same as lightbox, still might be more convenient in some cases though)
You can use tablet (the one with transparent layer, which allows to put A-side drawing/print beneath)
You don't need for this purpose expensive nor packed with features tablet, even cheapest simple A5 size should be more than enough!
Then you can skip whole "analog" part after converting your drawing into a digital version and proceed on your computer.
In this case you can use graphics software like Photoshop or GIMP (but in fact any application which is using layers and allows to set layer transparency will be perfect, so just pick the one you are most familiar with).
Just copy the layer with A-side drawing, put it above original A-side (and rename it to let's say B-side:) then lower newly created layer transparency so you can
see-through A-side. Then you can work directly on B-side OR create another one (or more) layers above B-side so you can work step-by-step,
switch on and off and easily correct/replace parts of created B-side.
Oh and you can do it both using mouse or pen (tablet) according to which one is more comfortably for you.
In fact I'm using all of above mentioned solutions, mixing these often - depending on project, specific of figurine or sometime just... mood!
Above mentioned techniques are OK when working with hand drawings (either with traditional paper and pencil or using tablet or after some tweaking by tracing or vector-drawing software like Corel, Illustrator, or any other including open formats like Inkscape etc.), but in any case you will need some degree of practice and skills to create (and then modify) the basic drawing.
Then there is also another one, fastest and most easy solution. And no drawing skills needed at all.Just download some FREE 3D modelling software (like FREE
DAZ Studio, comes first to my mind but there are also other packages, use Uncle Google's searchging:).
You will find that there are literally thousands of ready-to-use models available. Some are published on a commercial basis but there are also TONS of free stuff - already textured, with armour, accessories and weapons etc.!
All you need is to import interesting model, change posing (if needed as some models are already in "action poses"), perhaps add/remove some features, change colours or lightnings (all this it's all usually possible with simple checkboxes and slides), in fact you will just have to pay attention to proper perspective, so to avoid some funny, not typical / not usable for paper miniatures view perspective.
At the and just export (save) A and B view to to some raster graphic format which is most convenient for you or acceptable by your 2D graphick software in case if you will want do some further postprocessing). It's up to you whenever to save as B&W or colour/textured version.Actually you can use such created A and B views as:
a)templates or
b) ready figurines
Of course in any case you can add some layers with textures or graphic filters in order to modify some parts or even change the look of whole figurine.
You can find some amazing samples of 3D based figurines here at CW forums (vide @x3d or madmanmike just to mention recently viewed posts)
Please note, I'm not discussing legal use of downloaded models or art-related aspects (as some users might prefer less artifical or more dynamic posing/more character compared to 3D generated, as well as for some users more hand-drawn style or more cartoonish style might be more appealing) - speaking just from technical point of view.