Rav Meir explained in shiur today that Shmuel must hold like Rabbi Meir. But if Shmuel's only issue is that it not be מחוסר בידי שמים, why is it not enough to have all the raw materials even if it's not עד שיעשו?
1. Rav Meir mentioned in shiur that the drying is something that may be considered מחוסר בידי שמים.
2. the Shita quotes the Rivan that if all you have is dirt then it is not considered having ביצים של יוצר. This is also used to explain the end of the sugya with shitas chachamim -- during ימות הגשמים it has not been converted to usable zevel yet so it is like there is no zevel.