i personalty love the mod but cant consider adding it to my long term because the cost to upgrade a few items is too cheap when elastispacers are soo good late game with the mod so my recommendation is

uber/very expensive mode (for long term worlds)
these would be per upgrade

basic chest: 1 elastispacer in the middle with boards surounding
scaled chest: 1 elastispacer in the top middle slot and dragon scales around the outside
ice box: 1 elastispacer and gears around the outside
salt box: 1 elastispacer and blue gems around the outside
fish box: 1 elastispacer in top middle and malbatross feathers around the outside
ocean trawler: feathery canvas in every slot
tacklebox: malbatross feathers around outside
spectacklerbox: malbatross feathers around outside
wickerbottems bookshelf: 2 elastispacer in the middle and pure horror or living logs around the outside
magician's chest: 2 elastispacer in the middle and shadow atrium around the outside
polar bearger bin: 2 elastispacer in the middle and thick fur around

backpack: papyrus around the outside
piggyback: pig skin around the outside with rope at the top
chefs pouch: salt around the outside
isulated pack: gears around the outside with blue gems at the top
krampus sack: pure brilliance on left pure horror on right elastispacers at the top

for questions comments and concerns reach me in discussion or on discord @blockboyp
pls add to mod :)