you can use 25mm(c2c) bus bar for 4s1p. it is available from aliexpress "CHLBATT Factory Store"
https://www.aliexpress.com/item/1005002555457335.html?spm=a2g0s.9042311.0.0.63e84c4d8nRf47
In case of 4s3p, 55mm(c2c) bus bar can connect 3p by drill 6mm hole at center with regular drill, screw two...