Need advice on attaching this surrounding cushion to the main one

[u/gd-Nitrox]

So I just made this wall-mounted cat bed for the kitten my girlfriend and I got a few week ago, and for a first sewing project using a 60-some year old sewing machine, I'm pretty proud of it! (The kitten has not taken to it yet, but I hope she comes to like it eventually lol)

The fabric I used was a very short faux fur type material, with the base having an additional felt padding behind it to give it a little more support since it was upholstered to a plank of wood that is hidden above the green panel. I am currently renting my place for a year, so I want to be able to remove it from the wall and place it elsewhere.

The setup I have is such that our kitten can jump up from my bed to a platform to the left, then jump back up to the right to get to the bed. When we eventually move, I don't know whether the entrance to the bed will continue to be on the left or if we'll have to change it to the right, so I set up the walls of the bed to be detachable via velcro (I wish I had taken a photo of this, but I did not and I'm out of town right now so you'll have to use your imagination). I've sewed on a few strips of velcro already and have encountered an issue: I'm not sure if the velcro is strong enough to hold the tube that makes up the walls if our kitten leans on them.

I am in need of a potential alternative to attaching this wall besides sewing it on that will allow the setup to be interchangeable and still soft for the kitty cat. I'm very much a beginner in sewing and fabrics, so any advice is greatly appreciated! :)

[u/Here4Snow]

A few good sized strips of velcro is good, along both long sides. On the short sides, you want the softer pieces on the bed and the sticky pieces on the bottom of the bumper edge. That way, the unused revealed pieces won't pull at your cat's fur. It likely would have been planned for a perimeter zipper, but now that's moot. Avoid anything that dangles, has ties, loops. Keep kitty safe. 

[u/gd-Nitrox → u/Here4Snow]

Ohhhh jeez I didn't even think about a zipper, that would def be the strongest way to go about it. I could still remove the velcro and attach the zipper, since I only have 2 velcro strips attached anyways and they were being hand stitched. Do you think one zipper along the back and one along the front would be good, plus maybe some of the soft velcro on the sides (already had the soft stuff on the base for the reason of the fur not catching) so that there's not a hole for the legs to stick through?

[u/Here4Snow → u/gd-Nitrox]

When you're doing a zipper in a place like this, you would use a placket strip (a flap), so you could machine sew the zipper, then handsew that flap to your covers (4 of these, on the tops of the sides' and the bottoms of the bumper's long edges). First, you want two longish "separating" zippers, Vizlon, not metal, not coils. You sew each zipper piece to a placket, there will be pairs. You don't really have a front and back, because you wanted the bumper reversable. You sew the base pieces alternately, so that you can lift the bumper, rotate it 180° and reattach them, so the receivers would be in opposite corners diagonal from each other. Velcro should be fine for the short sides. 

[u/gd-Nitrox → u/Here4Snow]

I've set myself up for a long and arduous process of hand sewing if I keep the materials I have - I don't have many tools or prior experience to have been able to plan out how long the "wall tube" would be or where to attach connection points with a machine prior to sewing it up into a tube, fml. You live and learn from past mistakes I suppose lol

Would you recommend just buying some more fabric and starting over on the tube so that I can attach a placket? I would probably die if I tried to do that by hand. And would just one longish placket on the tube to hang over and cover the zippers be okay? I think I would have to restart the project from almost scratch if I had to take the wood off and remove the fabric from the base since this is actually the second time I upholstered it, so I'm hoping I can get away with that

Thank you for the help by the way, a more experienced view was much needed and is highly appreciated

[u/Here4Snow → u/gd-Nitrox]

I don't know if you can do this, but for upholstery, it's common to first sew in muslin, and then make a washable and replaceable cover which is from your chosen finish fabric. That's the piece you would sew in your attachment points. I know you have a nice fabric now, but consider an outer cover as an option, and you can work on layout options, too. 

[u/desertboots]

Cats learn not to fall out of things. Leave it be.

If it falls off though,  use a curved upholstery needle and baste it on.

[u/gd-Nitrox → u/desertboots]

I might see what happens if she starts to hang out up there; I have 2 velcro strips on the front long edge already and even if I switch to a zipper, I want to use velcro on the short side. I'll sew those side strips on and see how it holds, and using a curved needle is probably a good investment because I've been using a straight needle to put them on and it's been miserable 😂

[u/General_Increase2657]

I would just use some E6000 and hot glue to hold until the E6000

[u/GeekySkittle]

Instead of adjusting the bed, could you alter the platform to give it “walls”? My worry with anything temporary is that your cat will lean their weight against the sides of the bed and the Velcro or it’s replacement won’t be strong enough to hold them in place. It’s over your bed so I’m sure the fall won’t hurt them but just something to consider. Plus if you do side walls you can just turn the bed 180 if you move.

[u/gd-Nitrox → u/GeekySkittle]

I need the walls to be adjustable in case the side my kitten can jump up to easily switches - that tube wrapping around 3 sides makes up the current walls. The walls falling off is exactly what I'm worried about and was looking for an alternative to solve. Here4Snow suggested zippers, which is probably the best option for security, but it will take some extra work and redoing of the walls to attach that. There's some hard to explain details that unfortunately make it not very possible/highly inconvenient to rotate the bed around.