This is a partial spoiler, but I'm getting tired enough of being asked this question to write the answer down for posterity. (-:
Here's the scoop: each time you advance a level in any tech discipline, a new schematic is automatically added to
your repertoire and you immediately have the ability to build that device (provided you have the components to do it).
There is only one new schematic per level in each tech discipline, and that's the one you'll get; no randomness,
no choice. These automatic Arcanum schematics are all listed in the manual, and you can peruse them at length before
deciding which technology levels your character/s should aim for.
The rub: These aren't the only schematics available in Arcanum.
There are a whole bunch of other ones, which you can find scattered throughout the game like treasure. Some disciplines have
only three. Some have thirteen. Your carefully-planned party may find itself unable to build something really cool. And that would
suck. So here's a list of the so-called "found schematics" of Arcanum, so you can judge for yourselves. (I've left off two
schematics that are quest items, since there's no fear of your missing those.)
Found Arcanum Schematics:
Chemistry Level 1 Fortifier (restores energy) Electrical Level 1 Lemon-Potato Charges (equivalent to Chemistry charges) Explosives Level 1 Bullets (for pistols and rifles) Chemistry Level 3 Fuel Mechanical Level 3 Compound Bow (improved bow) Gun Smithy Level 4 High Velocity Pistol (improved fancy pistol) Electrical Level 6 Flow Disruptor (shield of protection vs. magic) Gun Smithy Level 6 Blade Launcher (improved elephant gun) Gun Smithy Level 6 Long Range Pistol (improved looking glass rifle) Herbology Level 6 Invigorator (cures fatigue and damage) Mechanical Level 6 Mechanical Dagger (improved fine steel dagger) Gun Smithy Level 7 Mechanized Gun (improved repeater rifle) Electrical Level 2 *AND* Smithy Level 1 Miner's Helmet (helmet lets you see in the dark) Smithy Level 2 *AND* Explosives Level 1 Pyrotechnic Axe (tech axe does extra fire damage) Electrical Level 4 *AND* Smithy Level 1 Charged Sword (tech sword does extra electrical damage) Electrical Level 4 *AND* Mechanical Level 2 Pyrotechnic Bow (tech bow does extra fire damage) Explosives Level 4 *AND* Gun Smithy Level 4 Flame Thrower (repeater rifle does extra fire damage) Chemistry Level 5 *AND* Electrical Level 4 Necromizer (creates undead) Explosives Level 5 *AND* Smithy Level 4 Concussion Grenade (more powerful version of Explosive Grenade) Electrical Level 6 *AND* Smithy Level 1 Electro-Armor (tech armor of protection vs. electrical attacks) Chemistry Level 6 *AND* Smithy Level 1 Envenomed Sword (tech sword does extra poison damage) Chemistry Level 6 *AND* Smithy Level 2 Envenomed Axe (tech axe does extra poison damage) Chemistry Level 6 *AND* Mechanical Level 2 Envenomed Bow (tech bow does extra poison damage) Mechanical Level 6 *AND* Electrical Level 3 Detonator Chemistry Level 6 *AND* Gun Smithy Level 4 Acid Gun (repeater rifle does extra acid damage) Herbology Level 6 *AND* Electrical Level 4 Reanimator (resurrects dead character) Chemistry Level 6 *AND* Explosives Level 5 Paralysis Grenade (paralyzes enemies) Chemistry Level 6 *AND* Gun Smithy Level 5 Tranquilizer Gun (puts enemies to sleep) Gun Smithy Level 6 *AND* Electrical Level 5 Tesla Gun (real ass-kicker of a weapon, fires bolts of electricity) Gun Smithy Level 6 *AND* Explosives Level 5 Grenade Launcher (I'm not sure if you need to keep supplying this with grenades or not) Mechanical Level 6 *AND* Explosives Level 5 Explosive Decoy (improved Clockwork Decoy) Mechanical Level 7 *AND* Smithy Level 1 Goggled Helmet (helmet increases perception) Mechanical Level 7 *AND* Smithy Level 2 Machined Plate Mail (tech armor increases STR and resistances) Mechanical Level 7 *AND* Smithy Level 2 Automaton (more powerful Mechanized Arachnid) Therapeutics Level 7 *AND* Chemistry Level 5 Brain Builder (increases INT, decreases STR) Therapeutics Level 7 *AND* Chemistry Level 5 Muscle Maker (increases STR, decreases INT) Herbology Level 7 *AND* Chemistry Level 5 Miracle Cure (heals to max) Therapeutics Level 7 *AND* Chemistry Level 6 Mental Inhibitor (prevents an enemy from spellcasting) Herbology Level 7 *AND* Mechanical Level 7 Medical Arachnid (Mechanized Arachnid with healing powers) Explosives Level 7 *AND* Mechanical Level 7 Time Bomb