If you have ever worked out the price of an electroporation cuvette you will realise that, at several dollars each, they are worth recycling.
Accounts on how amenable electroporation cuvettes are to recycling vary, but I find that as long as you treat them well it is possible to use single cuvette many times.
It's the metal parts of the cuvette you need to worry about the most – you need to get them clean of DNA and cells and dry again quickly to prevent corrosion.
So the key is to wash and dry as soon as possible after transformation.
My protocol is to wash with water first to clear away most of the residual cells/DNA, then treat briefly with HCl to destroy any remaining DNA – which you obviously don't want hanging around the next time you do a transformation – then wash with 70% ethanol. The ethanol rinses away the HCl and sterilises the cuvette but because it is volatile it makes it easy to dry the cuvette in air.
So the protocol in detail is:
1. Rinse the cuvette five times with purified water. Ensure, especially with 1-2mm gap cuvettes that the chamber is fully washed out in all washing steps.
2. Fill the cuvette with 0.2M HCl and allow to stand for 10 minutes (but no longer as this will promote corrosion).
3. Rinse the cuvette five times with 70% ethanol, again ensuring the chambers are fully washed.
4. Under a sterile hood if possible, decant the ethanol and use a pipette (or syringe and hypodermic needle for small gaps) to remove as much residual ethanol as possible.
5. Air dry for 60 minutes, then replace the cap.
…and now your cuvettes are ready to go again.