SCP Tower Defense: Easy solo Wanderer's Library with cheap towers, easy steps

Sumarize:
Get 6 coffee machine at lv 3 while getting 2 able lv 1
Upgrade 1 Able near corner to lv 2 and place 2 able nearby.
Get 1-2 coffee machines to lv 4 and get the bottom Able to level 3
From here farm all coffee machine max 1 by 1, then focus on Able (When he get max kill then upgrade another one)
You should also get Tickle Monster to lv 3-4 once you upgrade Able to lv 3-4
Focus on Able in 1 by 1 to get all crown then place Samsara nearby.
Laterly put Evolved D-Class in far away (avoid stun) and control target him (to avoid Tickle Monster getting killed) and upgrade only 1 of him.
Thats all, good luck.