In the wild, cats have to hunt if they want to eat — which means running, jumping, climbing. Indoor cat food, on the other hand, is often lazily lying in a full bowl, and the only physical exercise required from the cat is to duck his head. This lead to many issues, including excess weight and boredom — I'm not going to give a lesson about cat feeding, I advise you to google for this topic.

There is, however, a simple solution : puzzle feeders, or food puzzles. A puzzle feeder is a device with which the cat has to actually interact in order to get his food. It can either be physically stimulating (e.g. a simple ball with a hole for food to get out) or mentally stimulating, or both. In any case it should help the cat eating more slowly and stop when he's not really hungry anymore (which, in principle, happens sooner when you eat more slowly).

There are a number of commercial solutions, some of which are cheap yet quite interesting. But of course if you're reading instructables you must be more interested in DIY solutions. I started with simple devices such as a plastic bottle with a hole (works, but expect grease and crumbs of dry food everywhere in the room) or a small pot too thin for the cat head (works well, as long as it's fixed), but somehow wanted something a bit more stimulating.

Here comes the wooden cat puzzle feeder tower.

Disclaimer : This is my first wood work (and my first instructable), so don't expect professionnal tips… This project was mainly a pretext to get my hands on woodworking. In addition, English is not my first language, so expect grammatical issues and (in particular technical) vocabulary flaws.

Step 1: Make Plans

First, draw your device on a piece of paper (or a computer, or whatever). It will help you avoid obvious flaws, improve efficiency, get dimensions, etc. Below are plans for mine — sorry for the poor picture, I may redraw it later if needed.

How it works, from top to bottom :

you fill dry food on top, then close the lid ;
the cat presses on the levers, which makes food fall down on the first plateau — the "gate" comes back into position with its own weight and/or counterweight(s) ;
using his paws through the windows, the cat pushes the food into the hole — the plateau is slightly lower than the window, plus there are gaps on the sides, so he can't easily catch it ;
the cat repeats step 3 as many times as necessary (depending of the number of levels and the size of the holes) ;
the food finally falls on an inclined plan to be redirected in front of the tower.

It's a good idea to make a cardboard prototype and give it to your cat, it really helps improving things

Step 2: Gather Tools and Material

I thought this project would be a good opportunity to use my brand new Dremel. Actually, it turned out chisels were far more useful.

Here's the list of tools I used :

chisels ;
miter saw ;
file (metal file — couldn't find small grain wood file) ;
sandpaper ;
Dremel if you like ;
rebate plan (not necessary if you have a clean base) ;
brush (for varnishing) ;
string (for gluing) ;
pencil (missing in the picture).

Of course if you have access to a laser cutter or whatever suitable electric saws, it's for the better I guess — though I kind of liked working with chisels. At least you should get a cleaner result.

I guess the choice of materials is pretty open. At first I planed to use plywood, but it turned out my supplier wouldn't cut all the pieces and it would have been a pain to get straight edges with the poor tools I have, so I decided to hack a "surplinthe" (isn't there an English word for that ? It's a kind of skirting board that goes above an already existing baseboard) which had a nice oak aspect — though it was just a thin layer on top of MDF — and which was just the right size, both in width, thickness and length.

So I used :

a surplinthe (I'll use the term "skirting board" from now on, unless someone comes with a better name), 2200 × 120 × 5 mm ;
an old cutting board ;
a bar from an old broken baby chair.

Plus wood glue and varnish.

Step 3: Cut and Sand Pieces

Take dimensions from your plan, and cut the skirting board (or whatever your material is) into pieces. In my case the skirting board width was 120 mm, which was exactly what I had planed, so I just had to cut them to the correct length using the miter saw. The length was just enough to allow for two more pieces in case of issue — obviously, I eventually had to use them…

A small tip for sanding (a bit more) straight : stick a sheet of sandpaper with double sided tape on a plane surface (e.g. a table).

Step 4: Cut Joints

I decided the best way to take full advantage of the skirting board was to use box joints. Of course you can skip this step if you prefer butt joints or whatever else.

If you don't have a laser cutter or a joint saw, you're in for chisels. I used the following procedure :

mark parts which would be cut off in order to avoid errors — in addition, it helps when you know on which side you have room ;
precut joints with the miter saw ;
finish the work with chisels ;
put the other side against the already cut side, and go to 1 ;
adjust with chisels and file until both sides fit easily.

Do your best, but don't worry too much about precision, 0.5 mm precision is enough. Don't forget varnish will help filling the gaps.

Follow this procedure for each pieces. Regularly try to assemble subparts of the whole device to check everything is fine : it's probably easier to correct things now than at the end.

Step 5: Plateaux and Inside Parts

Remember that the hole of a plateau should not be on top of the hole of the plateau below — otherwise there is no point in having several plateaux. In addition, plateaux fit only two sides of the tower, in order to prevent food from being stuck in hardly accessible areas — incidentally, it makes it harder for the cat to catch food on a plateau.

I figured one 3 cm (diameter) hole per plateau would be enough. You can use a Dremel to make the hole — either with the circle cutter if you have it (I do), or by making drill holes around a circle then joining all holes (I used this technique for the axis, see later).

Then make grooves in outer pieces for inner pieces. I used the Dremel with a fine engraver to make the edges of the areas I had to dig, then dug with the 4 mm chisel, but it's also easy to do the whole thing with the chisel (though a bit slower).

If you want (I did), you can make a bevel for inclined planes.

Step 6: Axis and Levers

Just as I was wondering what I could use to make the axis, I saw this old broken wooden baby chair lying on the sidewalk near trashes, which bars were perfect for my purpose.

Cut a piece of the right length from a good-looking part of the bar. It is varnished and dirty (you can see a sample in the first picture), so first sand it with sandpaper.

We need to make three slits : on both edges for levers, and a large slit in the middle for the "gate". First I used the Dremel to make aligned holes. Don't worry too much about the alignment (as long as you use a drill-bit with a diameter smaller than the thickness of your "gate"), but it may help to make a straight groove first. Once you have your drill holes, join them, using another Dremel tool (cutting rather than drilling). Then, use chisels to straighten your slits and to make them the right width. Finally, sand the inside of the slits. For this I used a piece of sandpaper balled-up around the blade of a knife.

Adjust until the levers and middle plateau fit correctly.

Then make the hole for the axis in the upper sides of the tower. I couldn't use the Dremel circle cutter as the smallest circle size (3 mm) was too large, so I drilled holes along a circle, then joined them together. Finally I rolled the sandpaper sheet and used it to enlarge the hole until it fitted the bar loosely enough (at the end I used a small piece of sandpaper around the bar, blocked in one of the slit and with my thumb) — unfortunately I forgot to take a picture.

Assemble the levers and axis to check if it works well. If you did it without really calculating, you may need counterweights for the gate to get back in position. In addition, it's probably best to add circlips inside to prevent friction of the inner panel on sides.

Step 7: Test Assembly

As I already mentioned it's best to test partial assembly during all the work. Now it's time to test the full assembly and small adjustments. Hopefully everything goes well. I had issues with the upper front part, which would fit correctly on both sides but wouldn't keep the whole thing straight. As I had no spare parts anymore, I had to adjust it by making joints larger, so it has a crappy look, but anyway.

Step 8: Prepare Base

I thought this would be the easiest step, but actually it was the most painful.

I used an old cutting board : it's cheap and there is a groove on the circumference to help preventing food to get out. In addition, the one I got was large enough to make room for a water bowl.

However, old cutting boards may be quite dirty. I mean, deeply dirty. Sandpaper can't help (it gets greasy very quickly anyway), and chisels wouldn't make a large flat surface easily. Therefore I choose to use a rebate plane.

It's the first time I used one and I can't say I was satisfied by what I was getting. The grain was in the opposite way for some adjacent boards, which made it even more difficult. "Fortunately", the cutting board eventually splitted by itself. Since I had worked only on half of the board, it was the opportunity to restart from scratch and I finally managed to get something not too bad.

I then smoothed the board with sandpaper, and made grooves for the base of the tower.

Step 9: Varnish

I thought tainted varnish would give a nice exotic wood color, but it was a mistake, I believe natural color would have given a better result (but maybe was I just too generous on the quantity of varnish ?). Anyway, I varnished twice both the inside part and the outside parts, in four sessions, then once more the whole assembled thing. I hesitated about to-be-glued surfaces, but I decided to varnish them anyway in case they could seen from the outside. If you do so, don't forget that the varnish layers will modify the way pieces assemble (plus varnish drops tend to aggregate on surfaces which will be glued…). I advise to check by assembling the whole device before giving the second layer of varnish on the outside parts.

Step 10: Assemble and Glue

Nothing really difficult here if you followed everything and regularly made assembly tests.

The wood glue I used became transparent when dry — had I read the label or tested it, I would have been more generous… It dries in 15 minutes and you have 5 minutes to adjust things. Although it's comfortable enough, since the tower is relatively large and there are a number of pieces I preferred to assemble it in two parts (without considering the base).

In order to keep corners straight, use the tip of the tower as a guide.

You can use a vice or claws to keep the pieces altogether, but for such a shape it may be easier to use a string (thanks Alex for the tip). Tighten the string with a piece of wood or whatever.

Finally, plug and glue the tower into the base.

One more varnish layer and you're done.

Step 11: Give It to Your Cat

Wait for the varnish to be really dry (follow at least the instructions on the label, i.e. 24 hours or so : though it may seem dry, there may still be toxic emanations, better be safe for your cat…), then give it to your cat. Hopefully he'll enjoy it.