Magento2 custom extension

Hello - I am looking for magento 2 custom extension and here are the details. 1) We get some products in different weights like 182gm, 224gm, 236gm, 400gm etc and each time it varies so we are creating each weight as one product so to avoid this, we should able to input all the weights as comma separated and the price is calculated based on the weight the customer ordered like if the customer ordered less than 1kg, is one price , 1kg and above then one price & 5kg and above is one price. 2) Based on the weight entered by the customer, it should give options of the near by weights of both side. Ex: if the Products are in 340, 220, 300, 440 gms and customer enter as 500gm then we should show two options as 440gms and 520gm (330+220gm) and if customer select 520gm, then both 330 and 220gm should be removed/out of stock. 3) Similarly, we should able to use this solution for other products as well.