The concept of a clockwork soldier is equal parts fascinating and frustrating. Fascinating because the two elements are wildly incongruous; clockwork is often associated with children's toys, not the stuff of warfare, and frustrating because steampunk, the genre most closely associated with clockwork, has been touched upon so often as to become a cliché in and of itself. Now would probably be a useful time to mention that, of all the -punk genres, steampunk is my least favourite for two reasons. One, most of it seems to be Victoriana + cogs + airships = steampunk. Two, it's not actually a -punk genre; -punk implies deconstruction of a concept, while steampunk seems to romanticise the Victorian and Edwardian eras. I am sure there is deep and challenging steampunk fiction out there, but I have yet to find it.
As a result, I am deciding not to reference the steampunk genre at all for this project, unless I should find myself in dire circumstances regarding ideas and need something Right Now. Either that, or I will take steampunk and make it -punk.
The element I am particularly interested in is the soldier. The term 'soldier' has very different implications than, say, 'warrior', or even 'fighter'. 'Soldier' suggests a degree of discipline and organisation, of being part of a bigger unit or army. The concept of a soldier is also quite broad. They could be a mercenary, a military guard, a front line fighter, a guerilla, a combat engineer, a medic, a pilot (either of land or air vehicles), a paratrooper, a marine, a cavalry soldier (I can almost hear Phil shouting at his monitor), a special forces soldier, a militia soldier, a drafted soldier, a supersoldier...
There is also the question of rank, which will be critical in determining the nature of their space. Are they a commander, with a huge war room at their disposal, or a private with a dinky little billet not much better than a cell? Is the space shared? How does military discipline (or perhaps lack thereof) affect the layout of the room?
The other element, clockwork, is tantalisingly tricky. To me the most important thing is the time period in which the soldier exists. Are they in the far future, reaching back to simpler times through old technology, or are they in the past where clockwork is on the cutting edge? How does the clockwork integrate with the character? Are they a toymaker drafted into the military, are they partly or wholly clockwork themselves, are they a zany engineer with a fondness for clockwork gadgetry? Is the clockwork a metaphor for a strictly regimented military life? Are little clockwork gubbins stress relief or mementos? Do they have a suit of clockwork power armour? Does the clockwork replace a steam or internal combustion engine for convenience, having no fuel needs other than a pair of strong arms to wind it, like a knight without a squire might paint their armour black for easier cleaning?
I've probably typed way too much. My apologies if you sat and read all of that.