Mod adds weigh for selected items and blocks.
Using config file in MocConfig/weightmod.json you can change weight values for them.

Config values:

WEIGHTS_FOR_ITEMS and WEIGHTS_FOR_BLOCKS are dictionaries in which you can set weight for item/block
[for example if you add "game:crystalizedore-poor-" : 50 in _ITEMS, then every item which has "game:crystalizedore-poor-" in its code will have weight 50]

[If item/block's weight was already set using value from dictionary but it satisfies other name value then it won't be overwritten.

If you have the first record "game:-poor-cassiterite-": 42 and the second "game:crystalizedore-poor-": 71 in _ITEMS dictionary then for example "game:crystalizedore-poor-cassiterite-slate" will have weight 42]

WEIGHTS_BONUS_ITEMS  items which add weight bonus, at the moment it works for backpacks and for players cloths

MAX_PLAYER_WEIGHT  max weight player can carry (without bonus from bags and with full health). When overloaded player can not move, jump.

WEIGH_PLAYER_THRESHOLD  ratio of current weight to maximum weight when walkspeed starts to lower (0 < value <=1)

RATIO_MIN_MAX_WEIGHT_PLAYER_HEALTH if you set this variable to 0.4 then player maximum weight won't be lower than  (MAX_PLAYER_WEIGHT * RATIO_MIN_MAX_WEIGHT_PLAYER_HEALTH) even if player has 0.1 of his maximum health.

ACCUM_TIME_WEIGHT_CHECK - how often weight CAN be calculated (seconds), it won't be recalculated if player's health or inventories were not changed

CLASS_WEIGHT_BONUS let you set weight bonus for selected classes (class_name:bonus_weight)

If you want to set buff/debuff to player from your mod you can add a new value to entity.Stats["weightmodweightbonus"], mod get GetBlended on it during weight calculation.