A 1x1 cone with an inverted positioned screwdriver just might work here.
So, I'm saying just might based off the the halved cast line of Peggy's head.
The base peg of the horn/drill-bit would be too wide for the hole, but based off the cast fault line, which I hi-lighted in blue, there is a greater chance for the plastic halves to ease the slimmer screw ...
I've come up with five different ways to make a micro security camera that look like your reference image.
I'll run through the different methods in the image above from left to right 1 through 5.
Far left camera 1
Tile, Round 1 x 1 in black (the lens), Brick, Round 1 x 1 Open Stud in white (camera body), Plate, Modified 1 x 1 Rounded with Handle in white (...
While there could be various approaches building studless the easiest one would be with Tile, Modified 2 x 2 Inverted. These modified tiles have studs on one side, which fit under bricks and plates, and smooth surface on the other side.
Here is a prototype which features equal 6-stud (or 30 modules) long sides. Parts can be changed upon availability, but it ...
If the problem is that the base of the horn is too big to fit in the hole on the chanfron you have to make the former smaller or the latter bigger. Careful work with a file/scalpel, if you're good at that kind of thing. Remember that it's a lot easier to take a bit more off than to put a bit back.
Odd that the bow doesn't use a standard size stud anyway (...
There's a brick-built spiral staircase in the Pet Shop:
That's definitely the most common way to do it. You just build up around a central point. This can be expanded to use longer or wider steps:
You can also use 2x2 turntables if you need more strength and/or larger stairs:
Your second guess was correct. It's not just a wrench. It's listed as a Screwdriver/spanner on Lego.com:
This part was also included in several sets in the Games line as a human tool to remove tiles from the dice. It's unclear (at least to me) whether this part was intended to be used for tile removal when it was introduced in 1979. Here's an example from ...
A possibility might be using Horse Battle Helmet (unicorn) parts 89524 or 13745:
However I'm unsure if those would fit. The head geometry of the horse part in question (93083c01pb08) seems to be wider than the geometry of the horses in the castle sets (e.g. 10352c01pb03)
If you're not afraid to modify (cut and/or bend) one of the horse helmets, they might ...
When your function (such as an extending crane boom) gets to one limit or the other, this clutch gear ratchets instead of binding up the motor and all the gears in between.
ETA: Forgot the second question. It has appeared in many sets, most recently the Fairground Mixer.
According to the official description, these are for customizing the completed build:
This LEGO Batman toy playset includes 2 minifigures and children can customize their builds, minifigures and weapons with the included pack of 10 assorted Bat elements.
Is it possible that you are thinking of this goblet (2343)?
This part was fairly common, and it was introduced around 1985, so it was probably in your collection.
1x1 round plates attach securely to the top as shown in this lamp from the Pet Shop:
🎶 First three from what we can see...🎶
Part: 4735 Bar 1 x 3 with Clip and Stud Receptacle (Robot Arm).
Part 2958 Technic, Disk 3 x 3.
Part: 75c03 Hose, Rigid 3mm D. 3L / 2.4cm.
🎶Last two hidden from view...🎶
4 & 5. Part: 4085d Plate, Modified 1 x 1 with Clip Vertical - Type 4
(thick open O clip).
I can't see, but I can imagine two crossed ...
Great question. It sounds like you are building a fairly large ship. If the scale is large enough, brick-built sails can look quite nice. You can add shape, contour, and texture using various building techniques.
If you want to keep things simple, you could just use a single layer of bricks as was done in this basic sailboat model that was an in-store ...
As mentioned in another answer, there are dedicated pieces for this now.
But... 6x6x6 cube is plenty big enough to have a stud-reversing construction inside, then the bottom can be a simple 6x6 plate with regular smooth tiles.
For example put some of these inside the cube:
In the case of 87609, the piece was first used in 2010 as part of the grill/bumper assembly for vehicles that were the standard 6 studs wide. Its length would appear to be a result of its original purpose. Its width also allows for attaching two rows of detail:
99206 showed up first in 2012. Its design allows for a more compact construction in situations ...
According to LEGO, it's the BrickHeadz icon with the series number.
He also stands on a buildable baseplate with series number and BrickHeadz icon for easy display -- Batman Brickheadz LEGO Shop page
If they release another series of Brickheadz, those sets will probably have a similar piece with a "2" on it.
My guess would be that they wanted to include one in more sets; so they made a smaller (cheaper) version and took the opportunity to add functionalities, such as the technic axle remover or the flat end for removing tiles easily. If I'm not mistaken, this version works on jumper plates too; which wasn't the case with the old one.
Just today I tried to use it quite successfully as an alternative to suspension springs. Right now I don't have it assembled so I can't post a screenshot, but the idea is to wind up the pullback motor then attach it to your construction with a cross axis from one side and beams from another and limit its moving with some details. If you are interested in how ...
The 1x1 brick is both small enough to mean that you get edges no matter which way up it is, and has all the sharp edges and corners of the 2x2 brick, just packed into a smaller, more evil form.
That naturally leads to the headlight block, which has all the same features, but, if you are unfortunate, can also attack with the lip on the bottom.
This picture might explain the reason:
As you can see, arches form a nice circle to fit round modified plate. All fits well, except the very bottom. Making the bottom edge fit the plate/tile nicely would result in gap with a round piece. The curve of this arch brick isn't full 1/4 circle to make it flush with a tile/plate.
However you may ask "Why didn't ...
Yoshihito Isogawa made clock mechanisms from it (well... tic-tac generators) http://www.isogawastudio.co.jp/legostudio/modelgallery_model/b077.html
Majorna created a "programmable" pull back racer http://www.eurobricks.com/forum/index.php?showtopic=69748&#entry1744425
Using a cut-pipe into a clip-with-tube will let you build a secure and precise angle.
If you have a solid brick behind the headlight bricks you can fix the angle by cutting the pipe at the right length.
I'm not an EV3 expert, but my understanding is that continuous mode stores results into a buffer that can be read nearly instantly. Single mode will need to wait to hear a ping back before reporting results.
Continuous mode will give you a faster response time. However, if you are using a number of ultrasonic sensors, they may interfere with one another, ...
Minifig hands, officially, are not to be removed. Lego doesn't make many accessories that fit the arms of the minifigs. The arm is slightly larger than the standard bar piece and so normal claw-shaped attachments don't fit. The minifig handcuff piece, which does fit over the wrist, is larger than the standard claw pieces.
You'll need to look to third-party ...