Boot Tent /packashack /carannex /changing Tent

I wanted a packashack, but they are about £300. I'm a student, and I've just bought a car. I don't have £300. This is how I made my own DIY version, for £63.63
I'll be giving vaugeish direction on how I made mine.
I'm not affiliated with any links, I just genuinely found the products really good.

I used:

10m of ripstop nylon from here https://aemarket.co.uk/products/ripstop-fabric-material?variant=1685429059612¤cy=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=CjwKCAiAp4KCBhB6EiwAxRxbpLAf2EEp88FJPcGnjuK5YzGepqZ3JqvDr-8mrcHAVC0pSb1JvsA_kxoCyxUQAvD_BwE
(cheaper in bulk - team up with a friend if you're making one, doesn't have to be the same colour!) - any other waterproof material will work, this was the cheapest and most lightweight I could find, but not necessarily the most waterproof. Should be fine for showers, not storms.

Stick on zips from Amazon https://www.amazon.co.uk/dp/B01F13S2EQ/ref=cm_sw_r_cp_apa_fabc_8YXJ7E1Z8R6QTEZPDTK0?_encoding=UTF8&psc=1 (I also stitched them, but be aware that sewing machines really do not like stitching through the gluey bit!)

These magnetic hooks to "sandwich" the tent to my car https://www.amazon.co.uk/dp/B07K31LGPG?ref=ppx_pop_mob_ap_share

I bought a massive roll of webbing to make the tie down bits (but it's available cheaper in smaller amounts, I use it a lot in my sewing so bought in bulk) -
https://www.amazon.co.uk/dp/B07K2DSFY7?ref=ppx_pop_mob_ap_share

And then used some 6mm elastic I had left over from making masks at the start of the pandemic to put tent pegs or bricks through for staking it out and some damp proof course that my dad had lying around from putting on his shed (as the skirt).

You'll also need basic sewing supplies (thread, a sewing machine, tailors chalk) and a basic understanding of sewing/problem solving. You'll also need persistence.

For my design, you'll need a car with a boot(trunk) that opens upwards. I have a Citroen Berlingo (the MPV, not the van) and it's perfect. The boot opens up high enough for me to very comfortably stand under it. Be aware that however high your boot(trunk) opens is how tall your tent will be.
I haven't tested this design on any barn style van doors, but I'd be interested to know if anybody modifies this for their van! Let me know.

Unfortunately I didn't take photos of the whole process, so please make do with my scribbles.
The pictures are drawn as though you are looking inside the open boot of my car, from the rear of the vehicle.
Take your 10m of material, and with the boot open, throw it over the top of your car. Ideally, the width of the fabric will cover your car from the outermost edge of your boot, and over the hinge of the boot. Make sure that one end is on the floor, and have the excess material on the other side. Cut the excess off, but remember that it's easy to cut more off later. Not so easy to add extra.
This will form the sides, and the "roof" of your tent.
A friend could be helpful with this step.

With the material still on the car, and cut to size, mark on the material where the edges of the boot are, dividing the one long price of material into 3 parts, (as you look at it from the rear of the car) the left wall, the roof, and the right wall.

Take the material that you cut off the main piece, and hold it up against the only open side you have left. Make sure it's touching the floor, and cut off any excess. This part will later become the front, or the door. It might be helpful to stick the material up to the boot with magnets, or have a friend hold it, while you cut the bottom off.

Bring all of the fabric inside, and get overwhelmed by how much material there is. This is a natural part of the process. Clear the largest table you own of "stuff" and set up your sewing machine.
You want to stitch the "front" piece to the "left-roof-right" piece, making sure that the lines you marked on the "left-roof-right" piece line up with the corners of your "front" piece.
In the drawing - you're stitching the green piece to the red piece, along the black circled line.
If you want your tent to be super-waterproof, look into doing a flat felled seam. I just used a zigzag stitch for strength. I might have slight water ingress along my seams, but I'm not super worried about that.

You should have a 4 sided, boxy bag that fits over your boot now. Test it. Trust me on this one, go no further in this project until you've taken the boxy bag and put it over your boot. Make sure it fits. There will probably be areas where it's a little baggy, but that's fine. Too big isn't an issue, too small is.
While it's on your car, and on level ground, trim off any excess material on the floor. Don't make it too short, but don't have it long enough to be able to stand on it.
The picture is mine pre-trimming.

Add a skirt.
I used damp proof course because it added an element of rigidity to the bottom of the tent.
I pinned this on the tent while it was on my car, so that the damp proof course was half on the floor, with a little overhang.
If I were making this again, id use sewing clips instead of pins (so I make fewer holes in the material) and I would have actually attached the damp proof course INSIDE the tent, not on the outside. That way, the water would have run off the blue material, onto the skirt and onto the floor. The way I did it leaves a slight "ledge" between the fabrics for rain water to collect and seep in. I'm not super worried about this, since it's near the ground.
You can skip this step of you choose, I don't think it's massively important, but it does make it look professional.
Make sure you don't go AROUND the corners with damp proof course. It's sort of rigid, and won't bend in 2 directions at once. That's why you can see that mine has splits in it at the corners.

Once you have your skirt sewn on, it's time to add zips. My zips were incredibly easy to add, I lay the tent flat out on the ground, and stuck the zip exactly where I wanted it with the adhesive that comes on the zip (I stuck it with the zip zipped up). My zip was on the front, but there are no rules here - one zip on the front, or 2 zips on either side, go crazy! Just remember that zips are possibly leak-points, so if you want it super watertight, use fewer zips.
Once the zip was stuck to the fabric, I un-zipped it, and cut the fabric underneath to make the opening.
Do that as many times as you like for the number of zips that you want.
I then sewed a straight line of stitching really close to the zip teeth, just in case the adhesive failed.

I finished mine by stitching on webbing loops, with elastic though them in order to peg/weigh it down. I ended up with 8 on mine, - back left, middle of the left panel, left of the front panel, just left of the zip on the front panel, either edge of the "door", just right of the right zip, right on the front panel, half way back down the right panel and at the back of the right panel.
The picture shows house bricks though the elastics to keep the tent down in wind.

I used magnetic hooks to attach the tent to my car. Not only are they super strong, but they are also useful for hanging things, and the hook gives me a nice lever to pull the magnets straight up and off the car, instead of dragging them along and ruining the paintwork.
I considered adding a window to the top of the tent at this point, as the boot has a window in it, to let in more light. Ultimately I decided against that, since the material already lets a good amount of light in, and I was worried about adding unnecessary points for leaks to develop.
You could add a window with clear PVC, or a mesh bug net in front of your door here.
If you REALLY want yours to be waterproof, you can use "seam sealer", "seam sealing tape" or waterproof spray over your seams at this point, or you can choose not to and accept that you might be a bit damp like me.
If you want to use your tent to change in, it's a good idea to make some kind of curtain to block off the car windows, so you can't be seen in your tent from the front of the car. I might make a "washing line" with 2 magnets with hooks across the boot, and throw some material over it.

Use it as an extension of your living space when car camping, as a changing room when kayaking/surfing/mountain biking etc, a shelter to cook in (REMEMBER VENTILATION - keep the door open, and don't set your tent on fire- be reasonable), use it as sun shade, or a rain cover. It takes me about 2 mins to put up on my car by myself, so it can be whipped out in a rainy emergency!
I also love that I can shut my boot with it still attached. It collapses, and I will weigh it down if it's windy to stop big flappy noises/rips in the wind, but it gives you the option to set it up, and still open and close your boot freely.
It packs down small so you can keep it in your car too.
Please let me know if you make one, and any adaptations you make to yours. Also let me know if you need things clarifying in the comments, I'll always do my best to help ☺️