Baker's boards (wooden boards on which loaves were arranged prior to baking)

are [rabbinically] tamei (they lack a receptacle, but otherwise appear to be utensils in the way that they are used),

and of householders (which do not share this appearance of being a utensil)

are tahor;

if one dyed them red or saffron (or another color)

they are [rabbinically] tamei (as they now have the appearance of utensils).

A baker's shelf (made of metal)

that was fixed to a wall,

Rabbi Eliezer rules is tahor (as it is attached to a wall which is attached to the ground)

and the Sages rule it is tamei (as it was a utensil that was susceptible to tumah prior to being attached to the wall).

A mat (this was actually just a plain wooden board, upon which dough would be kneaded; others say this refers to a vessel used to hold water used in making bread),

of bakers is [rabbinically] tamei

and of householders is tahor;

if one made a rim for it from [all] four directions

it is tamei (as it now has a receptacle),

[but if subsequently] it is broken through from one side

it is tahor.

Rabbi Shimon says

if one prepared it [the householder's wooden mat] to slice [dough] on it

it is [rabbinically] tamei.

And similarly the rolling pin

is [rabbinically] tamei (as it would be used to carry rolled-out dough draped over it).

פרק טו משנה ג

The screen of a flour sifter (this was made of animal hair, which has the same status of wood; others say it was a chute that sat below the sifter to ensure that the flour did not spread out below)

of flour merchants

is tamei (although it lacked a receptacle, the merchant would collect any flour that got caught in this part, and so it acted as a receptacle)

and of householders is tahor (the householder was not as meticulous about collecting any flour that got caught in it).

Rabbi Yehuda says

Also (the mesh screen) of hair-braiders (this was used to catch anything that fell out of the hair)

is [susceptible to the] tumah of a seat

as daughters

sit on it and have their hair braided