Is CE marking mandatory for a one-time production intended for experimental use?
CE marking must be applied to a machine before:
* Being marketed for the first time in the EU;
* Or for the first time being put into service within the EU.
So on all machines, a CE marking must be affixed. For machines you can do all the work yourselves and no external inspections are required. In addition, you build the machine from purchasing parts and it is important to check that these parts meet the legal obligations. In other words, a user manual is included and a declaration of conformity.
Experimental machines may be placed and used without CE marking in the test phase. The condition is that the necessary additional safety measures are taken.