A customer has 2 pairs of Quad ESL57 speakers for sale with custom something SOLID Frames to use them stacked. The original legs and side panels also included so the can also be used as individual pairs.
They are in good working order. A few years ago I repaired one for him with broken transformer wire and recently rebuilt one with faulty EHT supply. Back in the 90’s they were all serviced by Quad and all have the clamp boards fitted to protect against overloading.