Hi Vladokv,
it's not too difficult:
1) H2 generating jar:
- Jar with a lid. Glue some (50cm) tube in top of lid.
- half fill jar with water, and a little KOH, and some aluminium foil. It starts bubbling - pure H2.
- Put lid on jar... Let H2 replace all air in the jar and tube...
2) Spark-chamber:
- Small plastic bottle with bottom cut off & lid on.
- 2 electrodes fixed into place (tape/glue etc), coming down through the open bottom of the bottle, or glued through the cap.
- Electrode wires connected to HV supply.
3) Bowl of water:
- Put spark-chamber bottle in water bowl - until it's full of water
- Put tube from H2 Generator under bottle
- Pure H2 gas fills bottle. Water seals it off.
Of course, the whole process is fraught with danger!
- KOH is nasty
- If air mixes with H2 - it will explode with the spark
- It would be a good idea to shield the apparatus - by putting it in a plastic box for example...
- etc. etc...
What do you think?

Regards, Tim