Query to get number of items from different table reference in another table
Something like this will work, though is not necessarily efficient on all DB engines:

select Project_ID,
count(distinct Bottle_ID) bottlesCount,
count(distinct Plastic_ID) plasticsCount,
count(distinct Glass_ID) glassesCount,
count(distinct Cup_ID) cupsCount
from Project
left join Bottles using (Project_ID)
left join Plastics using (Project_ID)
left join Glasses using (Project_ID)
left join Cups using (Project_ID)
group by Project_ID;