Please can you clarify for me, are nails, screws and blue tack considered מוקצה מחמת גופו because they have no use on Shabbos, or are they considered כלי שמלאכתו לאיסור which has heteirim, seeing that they can be reused, although i don’t think that they were deliberately made for reusing
Regarding blue tack I am not familiar enough with it to answer you. However regarding screws and nails, the point is not if they can be reused or not, rather do they have any other normal use aside for building. Therefore, they are considered a כלי שמלאכתו לאיסור that has no use other permitted use. Another example of this would be a candle, which isn’t used for another purpose other than burning. The candle may obviously not be moved לצורך גופו, as it has none. There is however much controversy if it may be moved לצורך מקומו -to use it place. Some Poskim regard it as a כלי שמלאכתו לאיסור and then it may be moved, others however consider it מוקצה מחמת גופו a full muktza, since it has no use on שבת. The Poskim say that it should not be moved unless very necessary.
Prohibit- Ran, Ritva, Shabbos 146b R’ Akiva Eiger Mishnayos Shabbos end of 4th chapter, Eshel Avrohom 308-12, Aruch Hashulchan 279-1, Chazon Ish 44-13, Be’er Moshe (Electric) 6, Orchos Shabbos 19-6, also vol. 3 Chapter 1, Shalmei Yehuda Preface Chapter 7 ftnt. 22,23. Permit- Rashba, Shabbos 146b, Magen Avrohom 308-31, Graz 30885, M:B Shar Hatzion 279-4, Tiltulei Shabbos For R’ Moshe Feinstein zt’”l, Shevet Halevi 10-59, however in 3-32 he says that since the Chazon Ish was stringent therefore we should do so.