Bubble level for Rolleiflex TLR

I have a bit of an odd requirement - I'm looking for a solution to attach a bubble level to my Rolleiflex TLR.

 

I'd rather something that doesn't permanently attach, or leave any permanent mark.

 

I had considered a small magnetic variety (here), which I just assumed would magnetically attach to the waist-level finder, when it is open and I am looking down into it, but I realised today that the waist-level finder is not ferromagnetic.

 

Do you have any other suitable, small, ingenious, cheap suggestions?

There are small bubble levels that fit a hot shoe (which the Rolleiflex doesn't have) that can be laid on the ground glass without causing any damage. B&H has them. To solve the same problem I found a keychain/level years ago that was slightly too long to fit on the groundglass and sawed off one end so it would fit. Anything magnetic won't work as most of the metal on a Rollei is aluminum.

Here :Wasserwaage bubble level - (31618) | eBay

 

Suits to Rolleiflex hot shoe

The modern, redesigned (and I think rare?) Rolleiflexes have a hotshoe, but not the original ones. Mine is a 3.5F, from the late 60s, with no hotshoe.

If the camera is on a tripod, perhaps the bubble level could be somehow attached to that.

How about this Novoflex?

Empire 5-5/8 in. Line Levels Set (2-Pack)-83038 - The Home Depot

Empire 5-1/4 in. Polycast Post Level-720 - The Home Depot

Glue a bubble level to a flat strip of aluminium or plastic with a 1/4" hole in it, and screw it into the tripod socket of the camera.

 

Anything not firmly fixed to a flat reference surface of the camera is going to be useless as a level.

Good advice, thanks.

 

This is what I've decided on...

https://www.amazon.co.uk/gp/product/B01GCF46UG/

And I'm going to do something a bit odd... using the screw from an unused quick-release plate that I have, I'm going to mount this plate upside-down to the bottom of my Rollei. That might seem a bit silly, because then I won't be able to see the bubble level, but I think I can't mount it the right way up because of the lip around the rim of the plate. Anyway, what this will give me is a good-sized, flat platform that just protrudes from underneath the camera. I'll take Rodeo Joe's suggestion of glueing another small bubble level on top of that little platform.

 

PS. This whole question was to get a solution that will work when hand-holding the camera. I didn't make that explicit earlier, but 90% of my shots are hand-held.

Here's another variant of the accesssory shoe level:

However, 15 Euros is multiples of the price I paid for it -- check around before buying.

 

A simple line level can be found at almost any hardware store, and can be mounted with rubber bands or velco if you're clever enough.

You could buy the Rolleiflex panorama attachment which features a bubble level.

Asking prices seem to have ballooned since I got mine years ago.

rolleiflex panorama head - Google Search