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[Sanda]

Hi,

I am wondering if anyone has any ideas about reinforcing a plastic/rubber (vinyl, can't find a specific chemical composition) yoga ball so that it is hard? I was thinking some sort of spray or paint but I don't know any products.

I asked around a bit already, and got paper mache as a suggestion, which I am very interested in trying because logically I can see it working and the price is very affordable. I also got a fiberglass suggestion, but the suggester decided that was not a good route to take because it is too expensive (I don't have a ventilator or anything like that either). I don't have a budget but I can't go super extravagant either. Whatever method it is doesn't have to be completely smooth, this ball will eventually be covered in fabric anyway so as long as there are no large bumps that's alright.

I'd really like input from people who have a good working knowledge of things like this or can at least hypothesize about what various techniques will work.

[StabbityBlkMage]

Well assuming it's a large ball (1ft - 2ft in diameter) I'd suggest fiberglass. The expense isn't that much, most likely about $50 total in supplies (resin, fibgerglass, paint brushes, cups).

As long as you work outside in a yard, patio and not indoors a respirator hasn't been particularly necessary.

Here is some of my work regarding fiberglass ranging from props, armor and mold jackets.

http://junkerscosplay.blogspot.com/

[Sanda]

Hi,

Thanks for your reply! The ball is closer to a meter I think I will look into fiberglass now though, I just thought it was extremely expensive for some reason. Do you think the price would jump up a lot since the ball is that big?

I asked around a few other places and people told me I could make it pretty darn sturdy with lots of layers of paper mache, made with wallpaper paste rather than other types of adhesives. That route seems pretty cheap, but also quite time consuming (which is okay by me honestly).

[StabbityBlkMage]

As far as cost increasing you might have to buy more fiberglass mat/cloth but the resin you should still have plenty of. 9sqft of fiberglass mat is like $7 local to me. Don't know what the price is in your region.

http://m.homedepot.com/p/3M-Home-Sol...Mat/202077814/

I can't speak for that wallpaper paste method of paper mache since I have never done it, but I'm confident fiberglass would be more durable by far. I mean fiberglass is used to make boat hulls and bathtubs.

[astillar]

You could calculate the surface area of the ball and then look up the local prices of fiberglass mat online. That would give you an accurate estimate of how much you'll need. One layer of mat should be enough for the prop, unless you plan on putting weight on the ball or throwing/rolling it around.
Paper mache will be cheaper, but the prop's going to be noticeably heavier than fiberglass. If you don't need to lift the prop, I suppose it wouldn't make much difference. But you will sacrifice some durability with paper mache.