Here is a list of what I've made so far:
Clapping
Bless all in room
Water
Corpse Collector
Coal -> Gem
Gem -> Refined Gem
Dim Door
Heavens Gate
Harm all in Mud
Create Newbie monsters
Torch maker

Anyone get more?

umm, create alcohol once.

i've 'seen' but never made a monkey box, press button, monkey runs out and hits someone or does something amusing, and runs back in

Oh yea I forgot about the monkey box!

I remember pushing the button on an instakill zap -apparatus.

wasn't there a good berry apparatus?

Oh yea +hp berries ...

Turn you into dragon
Start fire in any room without water, even indoors.
Monkey tea service
Booze

push button and you get banished, I think this is usually a one use item, or maybe it was the insta selfkill one that was always one use.

Just made a Remove Scar apparatus the other day..

Some that are missing, I will try and remember more...

Youth (one use only i think, unless 10 hour)
Random Cookie Delivery
The refining machine refines one type, not always gems
MechaMagical Megaphone
Clairvoyance
Whak-a-player (bashes random player in room for stun, i think it's based on dex or avoid)
The banish app was nice, it banished you, then the app appeared where you did.
There were two apps, one that hid you, and the other hid your identity (so the desc said A muscular gnome or somesuch. The identity one worked on all in the room.

been a while since I was gnome but some I can remember:

mirror image
dragonify

Torch creating machine.
Machine that makes a room dark. Seems permanent (until boot)
Dimdoor machine.
Machine that hits a player with club, stuns much and does 20 dam.
Machine that hosts a monkey that does something weird to random player.
Machine that dilivers a cookie to someone on your friendlist.
Machine that generates flowing water.
Machine that spits a glob of oil, and lights it. Works indoors, water- and entproof.
Shouting apparatus.
Machine that seems to summon outworld monsters.
Machine that obscures your shortdesc according to your race, gender, background and stats (A male magical gnome with slender physique).
Harm all apparatus. Breaks after 1 use.
Dragonify apparatus. Can't use skills/spells
Booze generating machine.
Machine that detects alignment of everyone in room.
Mirror image creating machine, doesn't seem to work in combat.
Goodberry generating machine. Berries heal HP, but you can't seem to eat them if not wounded.
Machine that turns coal to gems.
Machine that grabs corpses in rooms with mecha-magical arms and destroys them.
Machine that writes floating letters.
Apparatus that banishes user, apparatus comes with you.
Suicide booth, death by electricity.
Machine that wants ore, I guess it refines it or something.
Clairvoyance machine.
Machine that blesses players present.
Machine that summons an angel.
Applause apparatus.

That's what I have created so far.

I could actually buy an angel apparatus if soneone is selling.
10k or so seems ok to me

Contact me via tell or mail

Trandar