Hello All,
There seems to be some conflicting advice on the need for tourists to comply with an impending requirement for French drivers to carry breathalyser kits in their vehicles.
Here is a reply to an enquiry seeking clarification from the French Tourist Development Agency.
The word "should" scuppers any idea of a home made solution.

It would seem that the kits are likely to be widely available in garages,supermarkets and motoring outlets in France at about €1. The prices in the UK are pretty high and, it would appear, to be non compliant in the main.
I wonder which breathalyser manufacturer has a relative in the the French legastive?!