How can I make a food puzzle for my dog?

If you have a bit more $, patience, some good wood-working tools & a can-do attitude - another one I've made that both my cats (2) & dogs (3) enjoy is the slider puzzle (like pictured in the thread above) It can be simple (one column) or more complex. Suggestion: Start off simple! You will have to have: a solid piece of wood, a router or a chisel. Use a Dremel(R) rotary tool to cut slots

If $ is an issue - try this:
Use varying lengths of PVC pipe. Not to long! Soften the edges using the lighter technique; coupled with fine sandpaper & a bit of wax. You can get creative: cap the ends with actual caps - or angle your cut & fit a second pipe to elevate the puzzle. Cut or burn 4-6 small to med holes in the sides of the pipes. Be sure to make some of the holes smaller than the treats to be used; some a bit larger to allow the treat to drop out. Another one to try: Insert PVC pipe into a stuffed animal. A few tips: use an old stuffed animal. Not to cheap or easy to shred. Cut an opening; remove a good portion of the stuffing from the toy, set it aside. Take a PVC pipe. The width of the PVC pipe should allow it to be inserted into the stuffed toy. length of the PVC pipe should be such that it can be secured (length-wise) into the toy. Cut (or burn) 4-8 holes in various locations on the side of the pipe. Cut the holes in ONE SIDE ONLY! *See suggestion above for cutting holes in PVC* Cap the ends of the pipe ( a couple layers of duct tape works well!) Insert the pipe length-wise into the stuffed toy. Assure the pipe is long enough that it lays securely inside the toy. VERY IMPORTANT - the holes in the side of the pipe need to face the opening cut into the toy. If the pipe rolls or moves the treats will fall into the stuffed toy or the pipe will fall out. Sew or use "heavy-use" adhesive to secure a velcro closure onto the flap you've cut into the toy. There you go! The idea is to place treats into the PVC container, secured inside the stuffed toy. Close the access flap on the toy with your velcro. The dog must use his nose to locate the treats in the toy. The dog must learn to locate & then open the velcro to allow the treats to fall out of the holes in the PVC "container" fixed inside the toy. If the dog seems only minimally interested - use treats with a stronger scent.

I learned this form this site:
http://www.tudodecao.com.br/ but it is in portuguese so here is the explanation in english:

Use a coke bottle with lots of holes in it (at least 8) with the cap off at first. You can make the holes with a lighter, so that the plastic won´t cut, and the size of the holes should be just a bit bigger than the kibble or treats you put in the bottle.

Watch your dog while she eats/plays and take the bottle away if she bites it or if she isn't interested in it (don´t give it back to the dog quickly, wait a few hours until she is hungry again).

As you see that she learns to play with it, start puting the cap on the bottle, an then slowly introduce new bottles with 7 holes, than 6, 5, 4, 3, 2 and 1 hole so the play time lasts longer. If it gets too hard for her and she loses interest quickly go back to more holes on the bottle.

Its not durable...but coke bottles are easy to replace.

A quick and easy trick is to put a compressed bone or small rawhide bone inside a long cotton sock, then tie a knot in the sock. The dog can either work to untie the knot, or chew on the closed end to rip the sock and get to the bone.

I suggest looking in the related section below your account/question info.  By just asking a question you have led to answers!