This is closely related to the question about jamming plates underneath 2x2 round bricks, (and indeed prompted by a comment there), with differences explained later.

It is possible to attach a plate (or tile) to the underside of a square rectangular brick/plate/tile, between the wall and the tubes, like so:

plates connected to the underside of different bricks

Note how the distance between a brick's wall and its inner tube seems to be the same as the thickness of a plate:

detail of plate inserted into transparent brick

A few observations:

  • This connection feels looser (seems to have less clutch) than using a round brick.

  • For 1-stud-wide plates, this connection doesn't guarantee a straight angle. The edge of the plate sits loose inside the brick.

  • For post-2005 regular bricks (i.e. non-sloped), since they have thinned walls with notches at every stud, the connection is particularly flimsy. A 1-stud-wide plate just won't get any grip at all.

  • The walls of rectangular bricks are connected to each other, so bending a wall "outwards" (to jam a plate/tile inside) means bending or stressing the perpendicular walls (as far as I understand the physics of solid materials).


  • Is this connection "legal"? (i.e.: Does this connection stress the parts involved?)

  • Has this type of connection been used in any official sets?

  • 1
    I'm guessing the "thinned walls" comment is the key indication that Lego doesn't consider it legal - otherwise they'd have had to preserve the old style of wall.
    – RSchulz
    Commented Aug 6, 2022 at 14:47
  • Would this connection be considered "in system"? it seems the parts are offset by half a plate in two dimensions, and half a stud in the other, which would be in system. Commented Aug 7, 2022 at 23:15
  • 1
    Indeed - the offset is 4 LDUs (half a plate) in two axes. The plate, however, can slide along the third axis. This becomes obvious when using a 2x8 brick: a plate/tile can slide between the wall and the tubes. Commented Aug 7, 2022 at 23:25

2 Answers 2


To answer your second question: The technique was used by Lego in 1976's set 726 (12v Western train with 2 Wagons and Cowboys), to attach the horse's tail.

See page 13 of the instructions:

Steps of instructions showing the technique

  • 3
    Amazing! And look at the old legs used for the horse, too!
    – RSchulz
    Commented Aug 11, 2022 at 20:24
  • 1
    I'm not quite sure this is still legal, keeping in mind 46 years have passed since quoted use in 726 set. There are cases where TLG used certain building techniques, but then marked them as "illegal".
    – Alex
    Commented Aug 12, 2022 at 14:38
  • 2
    @Alex: That's why I didn't venture an opinion on the 'is this [currently] "legal"?' part of the question.
    – john_e
    Commented Aug 12, 2022 at 20:10
  • 1
    Great find! I remembered this technique from when I was a kid, but didn't know if it was in a set, or discovered by me. I could only find 'plate between studs' connections. Commented Aug 21, 2022 at 22:51

Some anecdotal evidence against legality: I have built such connections with rather old plates a long time ago and one of the outer plates failed (the wall breaking off). So it certainly puts the plates under some stress.

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