You can buy new ZX membranes from manufacturer:
http://www.ttklavesnice.cz/indexen.php (Czech)
membrane for ZX Spectrum 48+/Delta/ZX128+/ZS Scorpion ( TS5230036 )
membrane for ZX Spectrum 16/48 ( TS5230035 ) - BEST QUALITY
http://velesoft.speccy.cz/other/zx-membrane/ (membranes from WWW.TTKLAVESNICE.CZ)
http://www.qwerty.pl/ (Poland)
or
http://www.keypol.zgora.pl/index.php...st&iCategory=5 (Poland)
This membranes for ZX48+ can be used also to old KEYBOARD for ZS SCORPION. For using with other ZX clones must be used connectors for real membrane and create new keyboard