Stable Scratching Post??

[geniamaluca]

Hello, I'm new to the site and I couldn't find an answer to my question regarding this type of scratching post, but if there is an answer somewhere I'm sorry for asking this again!!

Every time my cat jumps on it, it wobbles and he gets scared. I've tried squeezing the post between heavy furniture, putting weights and/or sandbags on the base of the post, and sliding the tips of the base under heavy furniture as well. I can't screw or tape it onto the ground or anything like that because it's a rented apartment...
Is there any advice you can give me, please?

weight: 5kg | length: 88cm | width: 35cm | height: 140cm

(Sorry for the English mistakes!)

 

[basscat]

Buy a 6ft 2x4 (lumber). Cut it in half and screw the two pieces to the base. Thus making the base "footprint" larger and sturdier.