While some of us are lucky and have a lot of these, and some are willing to dish out the money these command on bricklink, I myself came up with a solution that works perfectly (for me at least)

You need:

1 x Axle 2L notched

2 x Axle 3L

2 x Liftarm 1 x 3 thin

2 x Plate, round 2 x 2 w/axle hole

2 x Pneumatic cylinder with two inlets (flat bottomed)

1 x Sword of Xact Zero, or similar cutting instrument.

Be warned, there will be cutting of plastic.

The final setup, as seen in the above picture, is - I imagine - at least as strong as it's expensive counterpart, while actually taking up less space, and it doesn't look half bad.

What you need to cut is ONE of the round plates and the 2L axle as in the above picture.

Cut the axle at both notches.

Cut the one round plate on the bottom. get rid of the "flanges" along the sides, as well as what's left sticking out in the middle. You shoul be left with a flat bottomed, very thin round disc with four studs on top.

The rest is pretty self-explanatory, but here is another picture

Disclaimer: If you just want to say "omfg you shouldn't cut parts blah blah blah" then don't bother. This is meant as a simple solution to a well known problem, without having to pay a small fortune. You could probably buy at least five of these (cylinders included) for the price of one set of brackets.

The problem is there is simply no way to legally join two pneumatic cylinders compactly and securely in the same manner as the brackets do, so I found this to be a good alternative,

I always knew they should make a 1L axle haha, anyway great idea!!

This is meant as a simple solution to a well known problem, without having to pay a small fortune. You could probably buy at least five of these (cylinders included) for the price of one set of brackets.

The problem is there is simply no way to legally join two pneumatic cylinders compactly and securely in the same manner as the brackets do, so I found this to be a good alternative,

Aha...

Or you can just simple connect two cylinders with Technic liftarms:

Or 2x2 tiles:

It looks simplier, but maybe I am wrong and cutting pieces is a better solution.

I've actually come up with a solution that does not involve cutting of parts, and allows one to connect modern round bottomed cylinders. I'll post the pics later, as my phone hates linking pictures.

Instead of cutting, couldn't you just use the turntable plate of the 2x2 turntable?

It might sound like heresy, but making this connection only 1-stud longer, we can avoid cutting, don't we?

Aha...

Or you can just simple connect two cylinders with Technic liftarms:

Or 2x2 tiles:

It looks simplier, but maybe I am wrong and cutting pieces is a better solution.

Are those cylinders red? i thought they only came in yellow did you paint them?

Are those cylinders red? i thought they only came in yellow did you paint them?

Those are the super old cylinders. They were in fact available in red.

Are those cylinders red? i thought they only came in yellow did you paint them?

Those are original red cylinders, but with only one input for a pneumatic hose.

Regarding connecting two cylinders, you can also use variant with 2x2 corner plate, and attach them as Mlonger showed, just with 2x2 corner plate.

There is solution as the OP showed in his first post, but without cutting. You can use 1x4 thin liftarms on sides, and between the cylinders use 2x2 brick and 2x2 plate, or better 2x2 round brick and 2x2 round plate.

No cutting, really strong, good looking.

I have seen similar connections with only square 2x2 plates. But have not tried it myself because I have 6 brackets.

Edited January 19, 201510 yr by vliet

Those are the super old cylinders. They were in fact available in red.

Ahh, now you're really making me feel ancient

Aha...

Or you can just simple connect two cylinders with Technic liftarms:

Or 2x2 tiles:

It looks simplier, but maybe I am wrong and cutting pieces is a better solution.

I wouldn't say it necessarily is a better solution, but it does offer some advantages over yours, mainly the cut 2L axle between the cylinders makes it impossible to move in the x- and y-direction.

I've actually come up with a solution that does not involve cutting of parts, and allows one to connect modern round bottomed cylinders. I'll post the pics later, as my phone hates linking pictures.

Looking forward to seeing it! I made a solution myself, where they (new, round-bottomed cylinders) were connected end-to-end (no gap between them), using 2L liftarms between the pinholes, as well as over the hoses on the lower inlets.. Maybe not exactly legal in some peoples' eyes that either, but it did offer a surprisingly strong connection

Instead of cutting, couldn't you just use the turntable plate of the 2x2 turntable?

I just tried, and if fits pefectly! Exact same thickness, but not as secure, as there is some play between that part and the 2x2 round brick

It might sound like heresy, but making this connection only 1-stud longer, we can avoid cutting, don't we?

that might be true, but I wanted it to be the exact length as the cylinder brackets

I should maybe show some of the advantages and possible mounting applicatons offered by this solution as well,

Here I used it with the 3x5 quarter ellipse thin liftarms in order to guide the hoses, as well as to make sure it doesn't turn when moving inside the crane arm (which has a 3-wide space inside)

Here I used it in an outrigger setup. Of course, you wouldn't need to connect the two here, you could just have two cylinders by themselves, but it makes the whole setup stronger.

Edited January 19, 201510 yr by D3K

If you use the technic cam, which has an odd 1 1/2 stud spacing, then you would be able to bring the cylinders back to back. The only downside is that you will need the thickness of 3-4 sheets of paper in between the bases as a shim. But it works for me and saves some space.

As promised, here are my ideas:

Pneumatic cylinder bracket by Saberwing007, on Flickr

It's very easy to make, and the track link can be substituted for a 3l liftarm.

Here is a detailed pic:

step2 by Saberwing007, on Flickr

Also, i figured out a way to join two old square bottom cylinders. just take 4 of the little pins with studs, plug them onto the end of one cylinder, and insert that into the base of the other, and secure with a pair of 3L liftarms and axles. It's most certainly not a legal connection, and it is very tight, but it works.