Oh , there are magnets prepared with adhesive foam out there  ?  That would be very easy .  I should have a look for that !

I use magnets on both parts.
On this...
VW 23 Window Bus 002 by Fred Maillardet, on Flickr
...I glued 4 magnets to the underside of the roof signage, taped it in place on the roof when dry and then after putting some glue in place I positioned magnets inside the roof.  They rotated themselves into the correct alignment for me and once the glue was dry (I used five minute epoxy) I could remove the roof signage and reattach as required.
VW 23 Window Bus 003 by Fred Maillardet, on Flickr
Magnets used were 4mm square neo magnets.

The Level 1 tests are done.

for this test, i have taken a BLU-109 JDAM from the spares box, slightly drilled the pinholes and placed a 1mm Neodyium magnet in each hole.



i have taken an old 1/144 Mini Hobby Models F-4E Phantom from the bone yard, and modified its 2 main pylons with 2 different means of attachments.

A: Neodymium attachments
B: steel needles (5mm long, 0,3mm thick)



on A, the magnets are spaced out, 4mm apart, just like on the test weapon.
this should give a better attachment compared to B (see later image).



on B, i have fitted 2 0,3mm steel needles, this should eliminate the need to check the poles before fitting the magnets.




Then, it was testing time, it would appear that option A, the magnet-to-magnet connection, appears to be the best option.
as for option B, the steel needles, the 2-same poles on the weapon, one side of the needless rejects the other, so that turns out to be a no-go for now.






so conclusion, it should work, if done right.
option A appears to be the best way to go, as shown is this diagram.

Thank you for that research 

I build something like that today ,  into my current project , a enterprise 1701 .
Instead of placing a  amazing amount  of  weight in the fuselage,  I try that with two magnets to hold it in place on the original stand .   I will tell you when the glue is hardened.

I bought some mini-magnets two years ago just to do the same thing, but haven't try it yet. I was still wondering what attachement system will be the best.

So thanks a lot @Spey_Phantom try out ! I will probably use the same technique in the F-8 and F-18 currently in building (not sure for the A-37 in 1/72 though. This thing is damn tiny, and the pylons very close to each others...) !

How did you manage to figure out the north and south pole of each magnet ? Do you have to check them individually ? 
As I want to be able to use the same payloads on different aircraft, I suppose I'll have to be extra cautious 

Just touch two of them  together, if they resist touching each other you've got two similar poles.

It doesn't matter if they're N or S, just that they're the same or different.  On the other hand, any pole will do if you're using a metallic something as a 'target' to attract the magnet, such a self tapping screw or similar.

Quote from: PR19_Kit on December 15, 2023, 04:04:02 AMJust touch two of them  together, if they resist touching each other you've got two similar poles.

It doesn't matter if they're N or S, just that they're the same or different.  On the other hand, any pole will do if you're using a metallic something as a 'target' to attract the magnet, such a self tapping screw or similar.

I know how to do it on a one to one basis. But as I wanted to equip 12 pylons and something like 30 weapons/tanks just for the current builds, I was wondering if there is some way to... industrialize the process, haha !

But I think I will (once and for all) just put some red marker on one side of every magnet. It's easy to do know, are they are all magneticaly aligned in their box, for the moment

And yes, I thought about using just a piece of metal for the pylons, but I just haven't find something that is thin enough and yet easy to cut at the right (small) dimensions. I thought about using needles too, but @Spey_Phantom is kinda disapointing about that.

Quote from: PolluxDeltaSeven on December 15, 2023, 06:31:47 AMAnd yes, I thought about using just a piece of metal for the pylons, but I just haven't find something that is thin enough and yet easy to cut at the right (small) dimensions. I thought about using needles too, but @Spey_Phantom is kinda disapointing about that.

Obvious I know, but better safe than sorry. Just make sure the metal is magnetic, most aren't.

Quote from: NARSES2 on December 16, 2023, 12:57:51 AM

Quote from: PolluxDeltaSeven on December 15, 2023, 06:31:47 AMAnd yes, I thought about using just a piece of metal for the pylons, but I just haven't find something that is thin enough and yet easy to cut at the right (small) dimensions. I thought about using needles too, but @Spey_Phantom is kinda disapointing about that.

Obvious I know, but better safe than sorry. Just make sure the metal is magnetic, most aren't.

So: thin enough, easy to cut, and magnetic !
If anyone as a good idea, I'm interested

Quote from: PolluxDeltaSeven on December 18, 2023, 05:23:48 AMSo: thin enough, easy to cut, and magnetic !
If anyone as a good idea, I'm interested

It's the easy to cut that's the difficult bit. An old razor blade is probably thin enough for the job and can be cut with a good pair of shears or a small hacksaw. Just be very, very careful with the blade's edge. If you can get a single edged blade it would probably be safer when it comes to cutting it.

Quote from: NARSES2 on December 16, 2023, 12:57:51 AMSo: thin enough, easy to cut, and magnetic !
If anyone as a good idea, I'm interested

you can find some thin steel foil in some hardware stores or online, preferably 0.3 or 0.1mm (or thinner).

Quote from: Spey_Phantom on December 18, 2023, 09:59:14 AMyou can find some thin steel foil in some hardware stores or online, preferably 0.3 or 0.1mm (or thinner).

That is thin, just had a look on E-Bay and was surprised by just how much of it is on offer. A lot is stainless and from China, and some stainless types (Austenitic grades) aren't magnetic. Now most stainless, especially flat products tends to be Austenitic.  From memory you need Ferritic/Martensitic grades.

Also noticed this https://www.ebay.co.uk/itm/145453556963?var=444621894812&hash=item21ddb524e3:g:JW8AAOSwlVllXcol&amdata=enc%3AAQAIAAAAwDVrE7%2Btu8PlEugNVwFMKE%2BXbUY8AGihdUyFY%2FMecUjmwTgHvXPt6ZdrrHH%2F%2BQr15F%2F4NUWZ6Z%2FgWGHGoGuPR8aP9JBIky9uUMu5AUWf%2BFZ5IrErxM0cWDQ9gTBclYvkAuL5xOZ5aLbE0aeb4Zjf9ynWt%2FpNeWXVMRkgn59OgbUJqnqWBNzVv1q6fo9jcidnj6Xofa0oVcKUrOeDburV4uw7uZbMqNTkrvRUtb7TFxWV1KVB%2FADE9RbgP5CNPEefdQ%3D%3D%7Ctkp%3ABk9SR-6696WQYw which they are calling plate/shim. Definitely safer than using an old razor blade 

Quote from: NARSES2 on December 19, 2023, 06:00:29 AMThat is thin, just had a look on E-Bay and was surprised by just how much of it is on offer. A lot is stainless and from China, and some stainless types (Austenitic grades) aren't magnetic. Now most stainless, especially flat products tends to be Austenitic.  From memory you need Ferritic/Martensitic grades.

Oooooohhh, getting into SERIOUS metallurgy here Chris. 

Quote from: PR19_Kit on December 19, 2023, 07:42:47 AM

Quote from: NARSES2 on December 19, 2023, 06:00:29 AMThat is thin, just had a look on E-Bay and was surprised by just how much of it is on offer. A lot is stainless and from China, and some stainless types (Austenitic grades) aren't magnetic. Now most stainless, especially flat products tends to be Austenitic.  From memory you need Ferritic/Martensitic grades.

Oooooohhh, getting into SERIOUS metallurgy here Chris. 

Yup a few trips around BS Stocksbridge and Avesta in both the UK and Sweden. 

Quote from: NARSES2 on December 19, 2023, 06:00:29 AM

Quote from: Spey_Phantom on December 18, 2023, 09:59:14 AMyou can find some thin steel foil in some hardware stores or online, preferably 0.3 or 0.1mm (or thinner).

That is thin, just had a look on E-Bay and was surprised by just how much of it is on offer. A lot is stainless and from China, and some stainless types (Austenitic grades) aren't magnetic. Now most stainless, especially flat products tends to be Austenitic.  From memory you need Ferritic/Martensitic grades.

Thanks for all the details !! I didn't know what to search for, but thank to you I may be able to find the right solution.

I may buy this product, just to test it:
https://www.wavgames.fr/feuille-metallique/15-feuille-metallique-200mm-x-300mm-adhesive-et-souple.html

200mm x 300mm x 0,25mm and compatible with magnets. It's even self-adhesive, so perfect for some tests and tryouts. Even if not perfect, it will still be safer than cutting a razor blade, haha !