This 15 ¾'' (400mm) Viola has been a commission by a player searching for a smallish instrument with a comfortable string length. After trying numerous smaller Violas  a body length of 400mm and string length of 352mm was found to be the most comfortable.
To maintain a good timbre in a smaller Viola it will benefit from a reasonable wide C-bout and slightly elongated ff-holes which will also give a lower bass fundamental to the belly vibrations, thus contributing to a rich bass sound.
For the body I adapted the outline of the classical and relatively broad model of Andrea Guarneri  to fit the above parameters.
The wood choice for it was a nice English sycamore slab back from Suffolk (not many remaining of that tree now), half slab ribs and an Italian split spruce front.
The unashamedly 'new look' oil varnish has a rich warm and transparent orange red colour.
After finishing it in March and some subtle sound adjustments it has been received with very good comments - now regularly played in Orchestras in Wales and also recently used in a private performance of Mozart quintets where its tone was very appreciated.

On commissioning a smaller Viola:
Often players don't consider that Viola designs have no fixed or standard ratios of body  and string length (unlike most violins) and will only ask for an instrument  in progressively smaller body lengths.
I believe that the body and string length can be seen initially - within reason - as almost separate entities.

We have learned from the classical makers that the bridge position can be almost in the geometrical centre of the front ( Brescian design) and further down (Cremonese design). This alters the  relative string length to body proportion.

Of course there might be a string length more ideal for a certain sonority of sound and 'ideal' tension for the standard strings....but by listening to individual players ideas/ concepts and looking at the physical possibilities of each player I believe that a customised small instrument with a real Viola sound is achievable.

I always ask  players to establish first  the maximum string length they can comfortably play on - without getting strains or tired. This might well be different if you are playing Wagner Operas every night or doing classical string quartet music or perhaps 'just' teaching.

After that consider a comfortable maximum body length of the Viola. This should enable you to maintain agility from the elbow, the wrist and ease of fingering up to high positions. As a player you are probably aware of this anyway.

The chosen string length gives me as a maker the correct length and proportion of the neck length and the stop of the belly (distance from edge of table to inner ff hole nicks) where the bridge stands at. This is  almost always at a ratio of 2:3, the same as in a violin. In a few cases it can be slightly altered but not by more then then a few mm's - as it affects  the left hand position changes  in relation to the neck root.

Considering also the type of sound quality and response you want I will then suggest a suitable model  which to use as a design prototype. This can then be rescaled and perhaps  slightly altered in proportions to achieve the desired stop/bridge position. Together with a suitable choice of tonewoods it is the first important step for a successfully customized Viola.