You can get both supernovium and compendium from scultping, and I think you can get supernovium rummaging in trash cans.
When travelling if you find enough dive well fragments you can reconstruct one and set whatever treasure you like to the dive well. Before you set the treasure, clone the dive well as many times as you want, and you can just keep diving for treasures (you can only use each dive well once).
I have a suggestion for those who would like to make the collecting harder (I also agree on harder) - have the quality of the items add up to make a multiplier for the total value, giving a final scoring value. That way, if you want it to be easy, you just use the easiest items to add up to the total value (was it 16k or 4k now??). If you want a higher scoring value, use higher quality items.
However, I still like the idea of complete collections, but removing the restrictions on how you complete the collection. If the butterfly collector challenge does indeed unlock the will-o-the-wisps, then I'm assuming it does something to the times that they spawn? Does anyone who knows the code have something to back this up? Certain collections would obviously require planning - but isn't that the point?
Lastly, the 150k LTHP is a cakewalk - at least for painters. I'm working on an immortal dynasty, and My first four painters were all elders when they joined the household, and easily achieved over 150k LTHPs - without wish enhancing serums.
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Edited to ask: Do school awards count as reward objects? Eg: valedictorian, most likely to offend etc? What about driving skill certificate? Trophies from after-class activities?