Experiment design useful when objects change / will be replaced in each trial run? I want to perform some studies on how material thickness, type of material, humidity and temperature influence tensile strength.
While I was thinking about useful designs I was wondering whether a certain design makes sense at all as I'll use for each investigation a new object.
Let's say a design experiment suggests for the first runs:
   Temperature humidity thickness
1  20 °C       50 %     1 cm
2  40 °C       30 %     2 cm
3  10 °C       30 %     1 cm
...

and so on.. so for each run I would use new objects and thus I would not keep the same object or material or device throughout the entire experiment.
Would I have to consider this somehow in a DoE?

The fact that the object changes from one run to the other is not an issue. As usual, the object-to-object variability will influence your inference. If the objects come by batches, then you can use blocking. In any case, DoE methodology applies here.
