Is there a way to get a kayak on the roof of a car with no roof rack?

I think foam blocks and straps will be ok for shorter distance trips.
Standard kayak kit - SportRack®

Since you have a chopped 4Runner, this Taco DIY rack might work : South Carolina Kayak Fishing - View topic - DIY Kayak Truck Rack

Thanks for the links! The bed in my truck isn't gonna be long enough for something like the Taco one, but the foam block thing is perfect, it wouldn't be for long hauls or anything, so I think that's the way to go until I get around to building the safari rack. Now I just need to get a kayak...

A cradle may be a better idea. I had bad luck with foam blocks. The plastic on the rounded crossbars made for a lot of slipping, especially at speed and turning. I've got a Yakima saddle and its much better.

I've done it bunch of times with a tandem kayak (Wilderness Systems 160T) which is about 55 lbs.

1. You can use those pool noodles. Cut in half, use tape (like electrical) to wrap.
2. I use 4 straps: bow, stern and two around the mid section that I got from home depot.
3. I've mounted the kayak upside down and right side up.

How do you do it? First you get a bathroom mat (with the rubber side) and throw that over the rear spoiler. I have a carrier with wheels that go into the scupper holes in the back of the kayak (when I'm kayak'ng by myself) so I lift the kayak by the front and place the front on the bath mat. I scoot myself back as the kayak will want to slide back and fall, so you need to make sure it doesn't move. Once you get to the rear of the kayak, you slide it forward over the pool noodles.

Taking the kayak off is roughly the same. You unstrap and slowly pull it back until only the stern portion is on the ground. Getting the kayak carrier thingy into the scupper holes is a bit tricky as it'll want to rock sideways but once you have it lifted and slide the mounts into the scupper holes, be careful as it'll want to slide back. Scoot yourself forward, lift the front off the bath mat and gently place on the ground.

I've lost 2 bath mats because I forgot to put them back into the 4Runner. Also if you have fold up seats, be sure to cinch down the straps to make sure they don't blow in the wind. I have no problem going 55MPH for 25-30 miles (Sand Harbor, Lake Tahoe).