crafting furnishings

So with the absence of my clan's crafter I've decided to get into it myself and I came across the furnishing that increases the great success chance. Do they stack the more I have up or no?

There are different types of Crafting Makerrs (EX, Art, Tech, Time), and you can only place one of each type (ie. you cannot place two Craft EX Makers together).

The only way to increase their effectiveness is to trade up to the the lv4 versions via the Craft Swap Shop, or by buying the S versions from the SG Shop which have the same effect as the lv4 versions and take up less space.