My PDP11 collection came about more by accident than anything else.   Working in the Health sector in the UK, where MUMPS is very important, it is quite usual to come across PDP11's that were running DSM-11

The collection

Dec Professional 350

PDP11/23+

PDP11/73 - Various OEM models and an original

PDP11/34 - My first UNIBUS machine

PDP11/44