I'm gonna post stuff in this thread, it's mostly for that. But feel free to add your own designs, they would be cool to see.
Here's a starter one, a little flying robot. It is shaped like a conventional drone, but the body is a tougher polymer. It has a lens and camera that is swivel mounted on the top to survey its surroundings. Inside the swiveling dome are heat sensors, and a light communications package. A concealed thermal scanning suite allows the drone to target heat signatures from a distance, as well as from behind soft cover. There is also a small ultrasonic sensor mounted on the front of the tube magazine, just below the the barrel. The wires run along the bottom of the mag and then to the central processing computer through an armored sleeve. Excess gas from the gun cycling is ejected downwards to avoid unnecessary loss of lift. The drone has only a small processor and simple, grunt-proof programming that lets it take instructions from a remote sender, it can't function at all without a connection to a remote. If it looses connection mid flight it is programmed to cease all actions except for hovering in place; this it will do until a connection is re-established or it's battery pack runs out. The weapon on the bottom is a .410 shotgun, along with a magazine of 10 shot shells. The firing rate is electronically limited to prevent too much destabilization. The machine's primary function is to collect reconnaissance data in environments with dangerous footing, or places that other machines cannot reach.
While I can't really design it yet, I've really been interested in advancing the effectiveness of ballistic plates and vests. They're bulky and constantly interfere with your accuracy, the plates themselves are pretty hefty too. I'd really like to see us manufacture and create a new polymer that would be more resistant to impact while being considerably lighter. What I look at is spider silk, which is already almost as tough in tensile strength than steel. If we can make something mimicking that to our standards(or make a spider that big lol) the potential is huge. Apparently I wasn't the first one to think of this.
And yet while kevlar has more tensile strength it isn't tougher. One sheet of kevlar will be more resistant than spider silk but the benefit of a make believe polymer that mimics spider silk would be of course it's weight and the ability to be compressed. I imagine you could compress 3-4 plates of this polymer into the size of one kevlar plate, while still being at least half as light.
These aren't so much machines as they are tools.
"Air Gun"
a water gun loaded with some sort of urethane rubber(something akin to liquid plastic / rubber) with a fast acting hardening agent.​ to be shot at the face.​ the substance should cover the mouth and nose.​ The victim's first reaction would be panic and scratch away at the hardened plastic/rubber(highly resistant to tears).​
Breathing would prove difficult and the liquid plastic/rubber wold be inhaled through the nostrils and mouth, essentially suffocating the victim.
"Drugbee"
A mechanical bee- kinda like this;http://giphy.com/gifs/l41lYvSntX992bLsk?utm_source=iframe&utm_medium=embed&utm_campaign=tag_click
With a capsule attached to its center. The capsule can carry either drugs, sedatives or poison. The capsule would have a retractable needle. Thin and flexible, the needle (microcannula) would be coated in anesthetic. To be used on political head figures, suspects and unruly children.