[toni-a]

Laowa just made a tilt and shift teleconverter, dunno why nobody thought of a tilt and shift extension tube !!!
it would be extremely handy for macro and not that hard to manufacture

[photonius]

The Laowa is only shift - and has optical elements specifically geared for the 12mm lens. So, it's not that universal.

But there are others available for quite a while, i.e. Kipon:
https://www.adorama.com/l/Lenses/Lens-Accessories/Lens-Adapters/Kipon~Lens-to-Camera-Tilt-Shift-Adapters

[Brightcolours]

Laowa just made a tilt and shift teleconverter, dunno why nobody thought of a tilt and shift extension tube !!!
it would be extremely handy for macro and not that hard to manufacture

As noted in above post.... Loawa did non just make a "tilt and shift" teleconverter. 

Why no-one thought of a tilt shift extension tube for the same format the lenses are made for: Lenses do not generally have a surplus image circle to accommodate for shifts.
And shift is not "extremely handy" for macro. Unless you want to correct receding perspective on those smurf house images.

[stoppingdown]

Yes. Already two years ago I bought some M-mount/Nikon-mount adapters, one which is only extension, and the other tilt (no shift). Basically, most of my macro work is made by means of the extension converters, which I enjoy a lot. For what concerns the tilting one, I've used it only a few times so far, but mostly because it requires a deeper understanding of things and more exercise on the field to begin pre-visualising what one wants to achieve. If one is interested, I'd recommend this approach. They are mechanical only and of different costs and quality. I've picked the cheap ones, in the range of 50-80€ if I remember well: the extension tubes are pretty fine (one maybe with an excess of lubricant), the tilt adapter plays a bit (but in the end the "play" effect is incorporated in the tilt effect).

[obican]

1. You can't really have a tilt&shift extension tube. The mechanical components will be so large, you won't be able to use most of your lenses at any reasonable focusing distances. Also since most native lenses only barely cover their native sensors anyway, you wouldn't get much tilt and shift out of them. You can maybe adapt a FF lens onto a APS-C sensor of the same system but then again, short focal lengths won't work at all since they'll probably focus somewhere inside the lens. Longer lenses will work but that's a really limited application.

2. You can make a tilt shift adapter and use FF lenses on APS-C and MFT mirrorless cameras. These things have existed for years. You can even buy one for medium format lenses and use them on full frame mirrorless. No idea if there is a medium format to DSLR tilt-shift adapter.

3. Hasselblad had a tilt shift teleconverter for years. Teleconverters work by making the image circle go larger, which lets you move the lens around to benefit from tilt and shift capabilities.

[JJ_SO]

...

2. You can make a tilt shift adapter and use FF lenses on APS-C and MFT mirrorless cameras. These things have existed for years. You can even buy one for medium format lenses and use them on full frame mirrorless. No idea if there is a medium format to DSLR tilt-shift adapter.
...

There are still a couple of macro bellows for tilt-shift purposes, but just in macro range. If one still has the lenses from negative enlargers (MF or bigger), these should deliver great quality. Best used as tethered units and preview the frame on a bigger screen than the normal LCDs.

[obican]

Yeah, Minolta had those even in the 70s. Tilting can be useful in some macro work.

[JJ_SO]

Nearly every manufacturer had a least a bellow to tilt the lens, I recall Zeiss and Nikon for sure. Shifting was more difficult and needed leses with a bigger image circle. Novoflex still makes such a bellow, high quality and price.

[obican]

Then again, Hasselblad had Flexbody and Arcbody



Can't fit a tilt-shift adapter between the lens and the body? Well, get rid of the body then!

[JJ_SO]

It's more Art to handhod the sensor in between.