All modified versions of the above you have successfully made a prototype of.
Since you already have the specialised tools and experience required to efficiently make the devices in your Portfolio, you can make such devices cheaply and comparatively swiftly. You can make one device from your Portfolio per turn, if you put a turnsheet action into it. If you let your apprentices make items from your Portfolio during your turn in housekeeping, they can make one such device - however, it will be clearly an inferior, apprentice-made product, and will not sell for as much as usual. If you and your apprentices work together, with you spending a turnsheet action supervising them, you can make three such devices - two of which will be good enough to pass off as your own work, one of which will be clearly apprentice-made. You must spend a Notable amount of money on each Portfolio device you wish to make.
New Innovations
Producing an entirely new and original invention is, obviously, the most difficult and time-consuming activity you can undertake as a clockworker. The process goes something like this:
1: E-mail the GMs and tell us what you want to do. We will e-mail you back telling you how viable the project is. We hope to be able to say "yes" to most ideas - the closer your invention adheres to the philosophy behind clockworking, the more likely this is to happen.
2: Spend 1 turnsheet action per turn for three turns producing the prototype of your invention. You will need to spend a Significant amount of money each turn on the prototype. Spending additional turnsheet actions per turn on producing your prototype will not speed things up; you cannot rush art. Your apprentices, if you have any, will not be able to help you to a significant extent during the production of the prototype; when producing prototypes intuition is just as important as theoretical understanding, and the interference of others is a hindrance, not a help.
3: Once your prototype is produced, you will now have a complete working example of your invention. Having gone through the process of making it once, you can now make additional copies of your invention much more efficiently - the design is now part of your Portfolio.
Gilding the Lily
Sometimes you will want to modify a device in your Portfolio. This is simplicity itself: simply spend a turnsheet action and a Notable amount of money on parts and tools, and you've successfully altered the design; the modified invention is now part of your Portfolio.
Backengineering
If you desire to work out how another clockworker's inventions function, you must spend one turnsheet action per turn for two turns painstakingly taking it apart to find out where all the bits go, and must spend a Significant amount of money on producing the specialised tools required to replicate your rival's achievement. Once you have done this, the device is now part of your Portfolio.
The Clockworker's Guild does not forbid its members to backengineer one another's works in this manner; after all, each clockworker's style is so distinctive that it would be hard to mistake one man's work for another's. Furthermore, devices produced by backengineering another clockworker's design tend not to not work quite as well as those produced by the original designer and his team.
The State of the Art
How developed is clockworking currently? Here's an overview of the current state of research in various areas:
Timepieces
Few further developments are possible in the field of timekeeping: the possibilities for greater precision and accuracy are quite exhausted by now.
Counting Devices
These are not especially advanced beyond simple adding-and-subtracting engines of the sort used by shopkeepers or Treasury tax assessors (and cash registers only appear in decidedly upmarket shops).
Automata
Clockwork machines in the shapes of men or animals which can undertake simple tasks or perform little tricks are prized by the nobility and are highly sought-after status symbols; an automaton produced by a famous clockworker is regarded in much the same way as one would regard a painting by a great artist. A concept that appears in lots of clockworking texts - both as a metaphor for the philosophy of clockwork, and as a hypothesised peak of the clockworker's art, is the production of a clockwork human which can think and reason like a real person. Such a creature has not never yet been produced. As far as anyone knows, that is...
Guns
Last - but certainly not least - all guns in the world of Horizon work using clockwork principles rather than gunpowder.
Varieties of Gun Available
Oneshot
The cheapest and simplest gun available. Disreputable clockworkers can crank several dozen of these out in a turn for some quick cash. A oneshot is very simply a gun barrel loaded with a single shot, powered by a cheap spring. It can be fired only once - after that, the spring breaks and the internal mechanism is ruined by the recoil, and one is left with a useless lump of metal. The main advantage of a one-shot is that it is easily concealed.
"Spring Kids", young toughs swaggering around armed with oneshots, are regarded with contempt by most of the criminal underworld. They're loud, they're rude, they're too rowdy to make good members of a gang and they attact too much attention from the Watchdogs. And their guns make them prone to do very stupid things: hardly a week goes by without a Spring Kid being sent to the Doghouse for shooting a rival Spring Kid or a Watchdog, or being snatched by the ghouls for killing some old lady in a bungled mugging attempt.
Oneshots are a Minor purchase. However, because these things are nasty, cheap, concealable, and dangerous, one-shots are illegal; it requires at least a turnsheet action to find an NPC clockworker willing to sell them to you, if you can't convince a PC clockworker to make you one. Furthermore, a warning to players of clockworkers: the Guild strongly disapproves of the production of one-shots (they consider them a perversion of the clockworker's art and a waste of talent), and are not liable to back you up if you are caught making them.
Rifles
A rifle is a Significant purchase. It is also difficult to conceal.
A rifle's mechanism is more robust and more powerful than a oneshot's, but it can still only load and fire one bullet at a time. It takes around half a minute to reload a rifle after it is used. They do have an impressive range, however - snipers swear by them.
The Watchdogs and Legions are the main purchasers of rifles in the city, and while it's not illegal for a civilian to carry a rifle around, it will get you far more attention than you'd enjoy from the Watchdogs; they are not used much in the criminal underworld.
Revolvers
A revolver is a Significant purchase, and holds six bullets. After a bullet is fired the revolver's mechanism moves the chamber with the next bullet into position - however, between shots the user must wind up the firing mechanism once more. This does not take long, however, and a firing rate of one bullet every few seconds is pretty damn impressive.
Automatic Rifles and Pistols
Automatic rifles and pistols are a Major purchase for a civilian - this reflects their scarcity as much as it does their complexity, since it is illegal to sell these weapons except to the Mayoral Legions or the armies of the Four Nations. Only licenced clockworkers may legally produce automatic weapons, and to apply for a licence one must: